619 + Interview Questions in NEWTONS-LAWS-OF-MOTION IN GENERAL AWARENESS Page 7 InterviewSolution

301.	A 8kg stone tied at the end of a string 1 metre long is whirled in a vertical circle. At the instant when the string makes an angle theta with the vertical, the speed of the stone is `4ms^(-1)` and the tension in the thread is 104N. Then theta is.A. `0^(@)`B. `30^(@)`C. `60^(@)`D. None of these
Answer» Correct Answer - C `T-mgcostheta=(mv^(2))/(r)` or `104-8xx10costheta=(8xx4xx4)/(2)` or `104-8costheta=64` or `80costheta=104-64` or `costheta=(40)/(80)=(1)/(2)` :. `theta=60^(@)` .

Discussion

302.	Find the friction force between the blocks in the figure-2.173: A. 6 NB. 18 NC. 5 ND. 12 N
Answer» Correct Answer - C

Discussion

303.	A body of mass ‘M’ collides against a wall with a velocity v and retraces its path with the same speed. The change in momentum is (take initial direction of velocity as positive)A. 2 mvB. mvC. `-mv`D. Zero
Answer» Correct Answer - A

Discussion

304.	Having gone through a plank of thickness h, a bullet changed its velocity from `v_(0)` to `v_(1)`. Find the time of motion of the bullet on the plank, assuming the resistance force to be proportional to the square of the velocity.
Answer» Correct Answer - `[(h(v_(0)-v))/(v_(0)vlog_(e)(v_(0)//v))]`

Discussion

305.	A smooth wire is bent into a vertical circle of radius a. `A` bead `P` can slide smoothly on the wire. The circle is rotated about vertical diameter AB as axis with a speed omega as shown in figure. The bead `P` is ar rest w.r.t. the circular ring in the position shown. then `omega^(2)` is equal to: A. `(2g)/(a)`B. `(2g)/(asqrt3)`C. `(gsqrt3)/(a)`D. `(2a)/(gsqrt3)`
Answer» Correct Answer - B As, `costheta=(a)/(2a)` `theta=60^(@)` :. `Nsin60^(@)=mg` `Nsin60^(@)=m(omega^(2)a)/(2)` :. `tan60^(@)=(2g)/(omega^(2)a)/(2)` implies `omega^(2)=(2g)/(asqrt(3))` .

Discussion

306.	An empty tin can of mass M is sliding with speed `V_(0)` across a horizontal sheet of ice in a rain storm. The area of opening of the can is A. The rain is falling vertically at a rate of n drops per second per square metre. Each rain drop has a mass m and is falling with a terminal velocity `V^(n)`. (a) Neglecting friction, calculate the speed of the can as a function of time,(b) Calculate the normal force ofreaction ofice on the can as a function of time.
Answer» Correct Answer - `[v=M(V_(0))/(M+mAnt),Fn=Mg+nAm(Vn+g t)" upwards"]`

Discussion

307.	A crate is pulled along a horizontal surface at constant velocity by an applied force F that makes an angle `theta` with the horizontal. The coefficient of kinetic friction between the crate and the surface is `mu`. Find the angle `theta` such that the applied force is minimum to slide the block. Also find the minimum value of this force.
Answer» Correct Answer - `tan^(-1)mu,(mmg)/(sqrt(1+m^(2))]`

Discussion

308.	Which one of the following statement s in not ture?A. The same force for the same time cause the same change in momentum for different bodies.B. The rate of change of momentum of body is directly proportinal to the applied force and takes place in the direction in which the force acts.C. A greater opposite force is needed to stop a heavy body than a light body in the same time, if they are moving with the same speed.D. The greater the change in the momentum in a given time, the lesser is the force that needs to be applied.
Answer» Correct Answer - D The greater the change in the momentum in a given time, the greater is the force that needs to be applied.

Discussion

309.	A body is struck to the front part of the truck. The coefficient of frction between the body and is `mu`. The minimum acceleration with which the truck should travel so that the body does not fall down is .A. `mu//g`B. `mug`C. `g//mu`D. `mu^(2)g`
Answer» Correct Answer - C

Discussion

310.	A 70 kg man enters a lift and stands an a weighing scale inside it. At time t = 0, the lift starts moving up and stops at a higher floor at t = 9.0 s. During the course of this journey, the weighing scale records his weight and given a plot of his weight vs time. The plot is shown in the fig. [Take `g = 10 m//s^(2)`] (a) Find `F_(0)` (b) Find the magnitude of maximum acceleration of the lift. (c) Find maximum speed acquired by the lift.
Answer» Correct Answer - (a) 93.3 N (b) `(10)/(7) m//s^(2)` (c) 4m/s

Discussion

311.	If force F=500-100t, then function of impulse with time will be,-A. `500t-50t^(2)`B. `50t-10`C. `50-t^(2)`D. `100t^(2)`
Answer» Correct Answer - A `I=int Fdt=500t-(100t^(2))/(2)`

Discussion

312.	When the two surface are coated with the lubricant, the they willA. roll upon each otherB. stick to each otherC. slide upon each otherD. none of the above
Answer» Correct Answer - C When two surface are coated with a lubricant reduces the friction and wear between them they slide upon each other.

Discussion

313.	A small coin is placed on a flat horizontal turn table. The turn table is observed to make three revolutions in `3.14 sec`. What is the coefficient of static friction between the coin and turn table if the coin is observed to slide off the turn table when it is greater than `10cm` from the centre of turn table .A. `0.4`B. `0.36`C. `4`D. `0.004`
Answer» Correct Answer - B `f = mromega^(2) ,f =mumg`

Discussion

314.	(a) A car starts moving (at point A) on a horizontal circular track and moves in anticlockwise sense. The speed of the car is made to increase uniformly. The car slips just after point D. The figure shows the friction force (f) acting on the car at points A, B, C and D. The length of the arrow indicates the magnitude of the friction and it is given that `angleD gt angleB gt angleC`. At which point (A, B, C or D) the friction forces represented is certainly wrong ? (b) A particle is moving along an expanding spiral (shown in fig) such that the normal force on the particle [i.e., component of force perpendicular to the path of the particle] remains constant in magnitude. The possible direction of acceleration`(veca)`of the particle has been shown at three points A, B and C on its path. At which of these points the direction of acceleration has been represented correctly. (c) A particle is moving in XY plane with a velocity . `vecv = 4hati + 2thatj ms^(-1)` . Calculate its rate of change of speed and normal acceleration at t = 2 s.
Answer» Correct Answer - (a) At C (b) At C (c) `sqrt(2) m//s^(2) "and" sqrt(2)m//s^(2)`

Discussion

315.	The apparent weight of the body, when it is travelling upwards with an acceleration of `2m//s^(2)` and mass is 10 kg , will beA. 198 NB. 164 NC. 140 ND. 118 N
Answer» Correct Answer - D

Discussion

316.	A constant force acting on a block of mass `5` kg changes `(a)` its speed from `6m//s` to `10 m//s` in travelling a distance `8m` in a straight line, (b) its speed from `2m//s` to `8m//s` in `3s` a straight line. Find the magnitude and the direction of the force.
Answer» As the force is constant, acceleration is also constant (a) `v^(2)=u^(2)+2as` `(10)^(2)=(6)^(2)+2axx8rArra=4m//s^(2)` `F=ma=5xx4=20N` (b) `v=u+at` `8=2+axx3rArra=2m//s^(2)` `F=ma=5xx2=10N`

Discussion

317.	A body of mass 2 kg is moving with a velocity `8m//s` on a smooth surface. If it is to be brought to rest in 4 seconds, then the force to be applied isA. 8 NB. 4 NC. 2 ND. 1 N
Answer» Correct Answer - B

Discussion

318.	A body of mass `8kg` is moved by a force `F = (3x)N`, where x is the disatance covered Initial position is `x =2m` and final position is `x =10m` If initially the body is at rest find the final speed .A. `6m//s`B. `12m//s`C. `18m//s`D. `14m//s`
Answer» Correct Answer - A

Discussion

319.	A paarticle moves in the xy-plane under the action of a force F such that the componentes of its linear momentum p at any time t and `p_(x)=2cos` t, `p_(y)=2sin` t. the eangle between F and p at time l isA. `90^(@)`B. `0^(@)`C. `180^(@)`D. `30^(@)`
Answer» Correct Answer - A

Discussion

320.	A `30kg` box has to move up an inclined plane of slope `30^(@)` the horizontal with a unform velocity of `5 ms^(-1)`. If the frictional force retarding the motion is `150N`, the horizontal force required to move the box up is `(g =ms^(-2))` .A. `300xx(2)/sqrt3N`B. `300xx(sqrt3)/(2)N`C. `300N`D. `150N`
Answer» Correct Answer - A `F cos theta = mg sin theta + f, f = mu_(s) N`

Discussion

321.	A block of mass m requires a horizontal force F0 to move it on a horizontal metal plate with constant velocity. The metal plate is folded to make it a right angled horizontal trough. Find the horizontal force F that is needed to move the block with constant velocity along this trough.
Answer» Correct Answer - `sqrt2 F_(0)`

Discussion

322.	A particle moving on the inside of a smooth sphere of radius r describing a horizontal circle at a distance `r//2` below the centre of the sphere. What is its speed ?A. `sqrt(5gr)`B. `sqrt(4gr//3)`C. `sqrt(3gr//2)`D. `sqrt(sqrt(3)gr)`
Answer» Correct Answer - C

Discussion

323.	Assertion: Frictional forces are conservative forces. Reason: Potential energy can be associated with frictional forces.A. If both assertion `&` Reason are True `&` the Reason is a corrrect explanation of the Asserion.B. If both Assertion `&` Reason are True but Reason is not correct explanation of the Assertion.C. If Assertion is Trie but the Reason is False.D. If both Assertion `&` Reason are false
Answer» Correct Answer - D Friction is non conservative, PE can not be associated.

Discussion

324.	A block of mass m is lying on an inclined plane. The coefficient of friction between the plane and the block is `mu`. The force `(F_(1))` required to move the block up the inclined plane will be:-A. `mg sin theta+mumg cos theta`B. `mg cos theta-mumg sin theta`C. `mg sin theta-mumg cos theta`D. `mg cos theta+mumg sin theta`
Answer» Correct Answer - A `F_("req")=mg sin theta+mu mg cos theta`

Discussion

325.	The coefficient of friction between a body and the surface of an inclined plane at `45^(@)` is 0.5. if `g=9.8m//s^(2)`, the acceleration of the body downwards I `m//s^(2)` isA. `(4.9)/sqrt(2)`B. `4.9sqrt(2)`C. `19.6sqrt(2)`D. `4.9`
Answer» Correct Answer - A `a=g sin theta-mug cos theta` `g((1)/sqrt(2)-0.5xx(1)/sqrt(2))=(9.8xx0.5)/sqrt(2)=(4.9)/sqrt(2)`

Discussion

326.	The masses of 10 kg and 20 kg respectively are connected by a massless spring as shown in figure. A force of 200 N acts on the 20 kg mass. At the instant shown, the 10 kg mass has acceleration `12m//sec^(2)` . What is the acceleration of 20 kg mass A. `1m//sec^(2)`B. `4m//s^(2)`C. `10m//sec^(2)`D. Zero
Answer» Correct Answer - B

Discussion

327.	Figure shows the position-time (x-t) graph of one dimensional motion of a mass 500g. What is the time interval between two consecutive impulses received by the body? A. 2sB. 4sC. 6sD. 8s
Answer» Correct Answer - A Figure shows that slope of `x-t` graph change from positive to negative at `t=2s` , and it changes from negative to positive at `t=4s` and so on. Thus direction of velocity is reversed after every two seconds. Hence, the body must be receiving conseccutive impulses after every two second.

Discussion

328.	Mass of block B shown in figure-2.218 is m and that of cart C is M. Show that the maximum value of force F such that the block does not slip over the surface of C, has a magnitude
Answer» Correct Answer - `F_("max")=mumg(1+(m)/(M))`

Discussion

329.	In the figure-2.219 shown, if the system is in equilibrium. Find the relation in `m_(1)` and `m_(2)` forthe case (i) if the bar is just going to slide and (ii) if box is just going to slide.
Answer» Correct Answer - `[(i)mu_(1)m_(1)g gt mu_(2)m_(2)g. (sinalpha-mu_(2)cosalpha)/(sinalpha+mu_(2)cosalpha)(ii)mu_(2)m_(2)g gt mu_(1) m_(1)g.(sinalpha+mu_(1)cosalpha)/(sinalpha-mu_(1)cosalpha)]`

Discussion

330.	An object of mass ` 3 kg ` is at rest. Now a force of ` vec F = 6 t^2 hat I + 4 t hat j` is applied on the object, the velocity of object at `t= 3 s` is.A. `18veci +3vecj`B. `18veci -3vecj`C. `3veci -18vecj`D. `3veci +18vecj`
Answer» Correct Answer - A `J =underset(0)overset(t)intF.dt,J=m(v-u)`

Discussion

331.	An impulse `vec(I)` changes the velocity of a particle from `vec(v)_(1)` to `vec(v)_(2)`. Kinetic energy gained by the particle is :-A. `I (v_(1)+v_(2))`B. `I(v_(1)+v_(2))//2`C. `I(v_(1)-v_(2))`D. `I(v_(1)-v_(2))//2`
Answer» Correct Answer - B `DeltaKE =(1)/(2) m(v_(2)^(2)-v_(1)^(2)),J =Deltap =m(v-u)` .

Discussion

332.	A ball is projected vertically up from the floor of a room. The ball experiences air resistance that is proportional to speed of the ball. Just before hitting the ceiling the speed of the ball is 10 m/s and its retardation is 2g. The ball rebounds from the ceiling without any loss of speed and falls on the floor 2s after making impact with the ceiling. How high is the ceiling? Take `g = 10 m//s^(2)`.
Answer» Correct Answer - 20 m

Discussion

333.	An automobile that is towing a trailer is accelerating on a level road. The force that the automobile exerts on the trailer is .A. equal to the force the trailer exerts on the automobileB. greater than the force the trailer exerts on the automobileC. equal to the force the trailer exerts on the roadD. equal to the force the road exerts on the trailer
Answer» Correct Answer - A

Discussion

334.	A rope of length `((pi)/(2) + 1)` R has been placed on a smooth sphere of radius R as shown in figure. End A of the rope is at the top of the sphere and end B is overhanging. Mass per unit length of the rope is `lambda` . The horizontal string holding this rope in place can tolerate tension equal to weight of the rope. Find the maximum mass `(M_(0))` of a block that can be tied to the end B of the rope so that the string does not break.
Answer» Correct Answer - `M_(0) = lambdaR ((pi)/(2) - 1)`

Discussion

335.	A uniform rope ABCDE has mass M and it is laid along two incline surfaces (AB and CD) and two horizontal surfaces (BC and DE) as shown in figure. The four parts of the rope AB, BC, CD and DE are of equal lengths. The coefficient of friction `(mu)` is uniform along the entire surface and is just good enough to prevent the rope from sliding. (a) Find `mu` (b) x is distance measured along the length of the rope starting from point A. Plot the variation of tension in the rope (T) with distance x. (c) Find the maximum tension in the rope.
Answer» Correct Answer - (a) `mu = (sqrt(3) + 1)/(sqrt(3) + 5) = 0.4 ` (c) `T_("max") = 0.17 Mg`

Discussion

336.	A uniform rope has been placed on a sloping surface as shown in the figure. The vertical separation and horizontal separation between the end points of the rope are H and X respectively. The friction coefficient `(mu)` is just good enough to prevent the rope from sliding down. Find the value of `mu`.
Answer» Correct Answer - `(H)/(x)`

Discussion

337.	A plate moves normally with the speed `v_(1)` towads a horizontal jet of uniform area of cross-section. The jet discharge water at the rate of volume `V` per second at a speed of `v_(2)`. The density of water is `rho`. Assume that water splashes along the surface of the plate ar right angles to the original motion. The magnitude of the force action on the plate due to the jet of water isA. `rhoVv_(1)`B. `rhoV(v_(1)+v_(2))`C. `(rhoV)/(v_(1)+v_(2))v_(1)^(2)`D. `rho[(V)/(v_(2))](v_(1)+v_(2))^(2)`
Answer» Correct Answer - D

Discussion

338.	Two billiard balls A and B, each of mass 50 kg and moving in oppsite direction with speed of `5ms^-1` each, collide and rebound with the same speed. If the collision lasts for `10^-3s`, which of the follwing statements are true?A. The impluse imparated to each ball is `0.25kg ms^(-1)` and the force on each ball is `250N`.B. The impluse imparated to each ball is `0.25 kg ms^(-1)` and the force exerted on each ball is `25xx10^(-5)N`.C. The impluse imparated to each ball is `0.5Ns`.D. The impluse and the force on each ball are equal in magnitude and opposite in direction.
Answer» Correct Answer - C::D Given `m_(1) =m_(2) =50(g) =50 xx 10^(-3) kg` Initial velocity `(u) = u_(1) = u_(2) = 5m//s` Final velocity `(v) = v_(1) = v_(2) = - 5m//s` Time duration of collision `= 10^(3)s` Change in linear momentum `=m (v-u)` `=50 xx 10^(-3)[-5 -5] = - 0.5 N -s` For `= ("impulse")/("Time") = ("Change in momentum")/(10^(-3) s)` `= (0.5)/(10^(-3)) =500N` Impulse and force are opposite in direction .

Discussion

339.	Assertion: It is difficult to move a heavy box by sliding whereas it becomes easier to move the same box when rollers are placed under it. Reason: `F_("rolling")ltF_("sliding")ltF_("limitting static")` (Rolling friction lt Sliding friction lt limmiting static friction.A. If both assertion `&` Reason are True `&` the Reason is a corrrect explanation of the Asserion.B. If both Assertion `&` Reason are True but Reason is not correct explanation of the Assertion.C. If Assertion is Trie but the Reason is False.D. If both Assertion `&` Reason are false
Answer» Correct Answer - A `F_("Rolling")ltF_("Sliding")`

Discussion

340.	Three weights W , 2 W and 3 W are connected to identical springs suspended from a rigid horizontal rod. The assembly of the rod and the weights fall freely. The positions of the weights from the rod are such thatA. 3 W will be farthestB. W will be farthestC. All will be at the same distanceD. 2 W will be farthest
Answer» Correct Answer - C

Discussion

341.	A car turns a corner on a slippery road at a canstant speed of `12m//s` . If the co0efficient is `0.4` , the minimum radius of the arc in metres in which the car truns is.A. 72B. 36C. 18D. 9
Answer» Correct Answer - B `F=mu(mg)` Centripetal force `F=mv^(2)//r` :. `mumg=(mv^(2)//r)` or `r=v^(2)//mug` or `r=((12)^(2))/(0.4xx10)=36m` .

Discussion

342.	Starting from rest a car takes at least ‘t’ second to travel through a distance s on a flat concrete road. Find the minimum time that will be needed for it to climb through a distance ‘s’ on an inclined concrete road. Assume that the car starts from rest and inclination of road is `theta = 5^(@)` with horizontal. Coefficient of friction between tyres and the concrete road is `mu = 1`.
Answer» Correct Answer - `(16t)/(sqrt(36-pi))`

Discussion

343.	A 20 kg bucket is lowered by a rope with constant velocity of 0.5m/s. What is the tension in the rope? A 20kg bucket is lowered with a constant downward acceleration of `1m//s^(2)`. What is the tension in the rope? A 10kg bucket is raised with a constant upward acceleration with same magnitude a.
Answer» Correct Answer - [200 N, 180 N, 220 N]

Discussion

344.	Six identical blocks – numbered 1 to 6 – have been glued in two groups of three each and have been suspended over a pulley as shown in fig. The pulley and string are massless and the system is in equilibrium. The block 1, 2, 3, and 4 get detached from the system in sequence starting with block 1. The time gap between separation of two consecutive block (i.e., time gap between separation of 1 and 2 or gap between separation of 2 and 3) is `t_(0)`. Finally, blocks 5 and 6 remain connected to the string. (a) Find the final speed of blocks 5 and 6. (b) Plot the graph of variation of speed of block 5 with respect to time, Take t = 0 when block 1 gets detached.
Answer» Correct Answer - (a) `(8gt_(0))/(15)`

Discussion

345.	(i) Four small blocks are interconnected with light strings and placed over a fixed sphere as shown. Blocks A, B and C are identical each having mass m = 1 kg. Block D has a mass of m´ = 2 kg. The coefficient of friction between the blocks and the sphere is `mu = 0.5`. The system is released from the position shown in figure. (a) Find the tension in each string. Which string has largest tension? (b) Find the friction force acting on each block. [Take `"tan"37^(@) = (3)/(4) , g = 10 m//s^(2)`] (ii) A fixed square prism ABCD has its axis horizontal and perpendicular to the plane of the figure. The face AB makes `45^(@)` with the vertical. On the upper faces AB and BC of the prism there are light bodies P and Q respectively. The two bodies (P and Q) are connected using a string `S_(1)` and strings `S_(0)` and `S_(2)` are hanging from P and Q respectively. All strings are mass less, and inextensible. String` S_(1)` is horizontal and the other two strings are vertical. The coefficient of friction between the bodies and the prism is `mu_(0)` . Assume that P and Q always remain in contact with the prism. (a) If tension in `S_(0)` is `T_(0)`, find the minimum tension `(T_(1))` in `S_(1)` to keep the body P at rest. (b) A mass `M_(0)` is tied to the lower end of string `S_(0)` and another mass `m_(2)` is tied to `S_(2)` . Find the minimum value of m2 so as to keep P and Q at rest.
Answer» Correct Answer - (a) `T_(BC) = 10N ; T_(AB) = 12N ; T_(AD) = 7N` (b) `f_(C) = 0 ; f_(B) = 4N ; f_(A) = 5N ; f_(D) = 5N` (ii) (a) `T_(1) = ((1- mu_(0))/(1 + mu_(0))) T_(0)` (b) `m_(2) = ((1 - mu_(0))/(1 + mu_(0)))^(2) M_(0)`

Discussion

346.	A block A has been placed symmetrically over two identical blocks B and C. All the three blocks have equal mass, M each, and the horizontal surface on which B and C are placed is smooth. The coefficient of friction between A and either of B and C is `mu`. The block A exerts equal pressure on B and C. A horizontal force F is applied to the block B. (a) Find maximum value of F so that A does not slip on B or C and the three blocks move together. (b) If F is increased beyond the maximum found in (a) where will we see slipping first- at contact of A and B or at the contact of A and C. (c) If F is kept half the maximum found in (a), calculate the ratio of friction force between A and B to that between A and C. Does this ratio change if F is decreased further?
Answer» Correct Answer - `F_("max") = (3)/(4) mu Mg` (b) Between A and B (c) 2 , No

Discussion

347.	The time in which a force of 2 N produces a change of momentum of `0.4kg-ms^(-1)` in the body isA. `0.2s`B. `0.02s`C. `0.5s`D. `0.05s`
Answer» Correct Answer - A

Discussion

348.	In the last problem, the rope is placed on the cylinder as shown. Find maximum tension in the rope.
Answer» Correct Answer - Zero

Discussion

349.	In the last problem if it is allowed to apply the force F in any direction, find the minimum force `F_("min")` needed to move the block on the incline.
Answer» Correct Answer - `F_("min") = (mg)/(2sqrt2)(sqrt3-1)`

Discussion

350.	Repeat the last problem if the graph is as shown below.
Answer» Correct Answer - 4.8 kg

Discussion

Explore topic-wise InterviewSolutions in .

A 8kg stone tied at the end of a string 1 metre long is whirled in a vertical circle. At the instant when the string makes an angle theta with the vertical, the speed of the stone is `4ms^(-1)` and the tension in the thread is 104N. Then theta is.A. `0^(@)`B. `30^(@)`C. `60^(@)`D. None of these

Find the friction force between the blocks in the figure-2.173: A. 6 NB. 18 NC. 5 ND. 12 N

A body of mass ‘M’ collides against a wall with a velocity v and retraces its path with the same speed. The change in momentum is (take initial direction of velocity as positive)A. 2 mvB. mvC. `-mv`D. Zero

Having gone through a plank of thickness h, a bullet changed its velocity from `v_(0)` to `v_(1)`. Find the time of motion of the bullet on the plank, assuming the resistance force to be proportional to the square of the velocity.

A body is struck to the front part of the truck. The coefficient of frction between the body and is `mu`. The minimum acceleration with which the truck should travel so that the body does not fall down is .A. `mu//g`B. `mug`C. `g//mu`D. `mu^(2)g`

If force F=500-100t, then function of impulse with time will be,-A. `500t-50t^(2)`B. `50t-10`C. `50-t^(2)`D. `100t^(2)`

When the two surface are coated with the lubricant, the they willA. roll upon each otherB. stick to each otherC. slide upon each otherD. none of the above

The apparent weight of the body, when it is travelling upwards with an acceleration of `2m//s^(2)` and mass is 10 kg , will beA. 198 NB. 164 NC. 140 ND. 118 N

A constant force acting on a block of mass `5` kg changes `(a)` its speed from `6m//s` to `10 m//s` in travelling a distance `8m` in a straight line, (b) its speed from `2m//s` to `8m//s` in `3s` a straight line. Find the magnitude and the direction of the force.

A body of mass 2 kg is moving with a velocity `8m//s` on a smooth surface. If it is to be brought to rest in 4 seconds, then the force to be applied isA. 8 NB. 4 NC. 2 ND. 1 N

A body of mass `8kg` is moved by a force `F = (3x)N`, where x is the disatance covered Initial position is `x =2m` and final position is `x =10m` If initially the body is at rest find the final speed .A. `6m//s`B. `12m//s`C. `18m//s`D. `14m//s`

A paarticle moves in the xy-plane under the action of a force F such that the componentes of its linear momentum p at any time t and `p_(x)=2cos` t, `p_(y)=2sin` t. the eangle between F and p at time l isA. `90^(@)`B. `0^(@)`C. `180^(@)`D. `30^(@)`

A block of mass m requires a horizontal force F0 to move it on a horizontal metal plate with constant velocity. The metal plate is folded to make it a right angled horizontal trough. Find the horizontal force F that is needed to move the block with constant velocity along this trough.

A particle moving on the inside of a smooth sphere of radius r describing a horizontal circle at a distance `r//2` below the centre of the sphere. What is its speed ?A. `sqrt(5gr)`B. `sqrt(4gr//3)`C. `sqrt(3gr//2)`D. `sqrt(sqrt(3)gr)`

The coefficient of friction between a body and the surface of an inclined plane at `45^(@)` is 0.5. if `g=9.8m//s^(2)`, the acceleration of the body downwards I `m//s^(2)` isA. `(4.9)/sqrt(2)`B. `4.9sqrt(2)`C. `19.6sqrt(2)`D. `4.9`

Figure shows the position-time (x-t) graph of one dimensional motion of a mass 500g. What is the time interval between two consecutive impulses received by the body? A. 2sB. 4sC. 6sD. 8s

Mass of block B shown in figure-2.218 is m and that of cart C is M. Show that the maximum value of force F such that the block does not slip over the surface of C, has a magnitude

In the figure-2.219 shown, if the system is in equilibrium. Find the relation in `m_(1)` and `m_(2)` forthe case (i) if the bar is just going to slide and (ii) if box is just going to slide.

An object of mass ` 3 kg ` is at rest. Now a force of ` vec F = 6 t^2 hat I + 4 t hat j` is applied on the object, the velocity of object at `t= 3 s` is.A. `18veci +3vecj`B. `18veci -3vecj`C. `3veci -18vecj`D. `3veci +18vecj`

An impulse `vec(I)` changes the velocity of a particle from `vec(v)_(1)` to `vec(v)_(2)`. Kinetic energy gained by the particle is :-A. `I (v_(1)+v_(2))`B. `I(v_(1)+v_(2))//2`C. `I(v_(1)-v_(2))`D. `I(v_(1)-v_(2))//2`

A car turns a corner on a slippery road at a canstant speed of `12m//s` . If the co0efficient is `0.4` , the minimum radius of the arc in metres in which the car truns is.A. 72B. 36C. 18D. 9

A 20 kg bucket is lowered by a rope with constant velocity of 0.5m/s. What is the tension in the rope? A 20kg bucket is lowered with a constant downward acceleration of `1m//s^(2)`. What is the tension in the rope? A 10kg bucket is raised with a constant upward acceleration with same magnitude a.

The time in which a force of 2 N produces a change of momentum of `0.4kg-ms^(-1)` in the body isA. `0.2s`B. `0.02s`C. `0.5s`D. `0.05s`

In the last problem, the rope is placed on the cylinder as shown. Find maximum tension in the rope.

In the last problem if it is allowed to apply the force F in any direction, find the minimum force `F_("min")` needed to move the block on the incline.

Repeat the last problem if the graph is as shown below.