InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1701. |
A freely falling object eventually stops on reaching the ground. What happens to its kinetic energy? |
| Answer» Solution :When an object falls freely towords the ground, its POTENTIAL ENERGY decreases and kinetic energy increases. As the object touches the ground, all its potential energy gets converted into kinetic energy. As the object hits the HARD ground, all its kinetic energy gets converted into heat energy and SOUND energy. It can also deform the ground depending UPON the nature of the ground and the amount of kinetic energy possessed by the object. | |
| 1702. |
A force of 5 N is acting on an object. The object is displaced through 2m in the direction of force. If the force acts on the object all through the displacement, thenfind the work done on the object. |
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Answer» Solution :WORK done on the object, `w=Fs` `=5Nxx2m` `=10NM` `=10J` |
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| 1703. |
The kinetic energy of the object |
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Answer» DEPENDS only on its MASS |
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| 1704. |
Rockets are used to launch artificial satellites. Write down the life situations related to this law. |
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| 1705. |
When a midrib of a coconut leaf, pencil etc. are dipped in water, and taken out, water is seen sticking to them. Why? |
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| 1706. |
A solid weighs 120 gf in air and 105 gf when it is completely immersed in water. Calculate therelative density of solid. |
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| 1708. |
Two diatomic gases A and B of masses 12 g and 32g occupy volumes of 1200 ml and 1920 ml , respectivey . When sound waves are passed through these gases , in which gas does sound travel with least velocity and also by how many times ? Assume that the pressure and temperature are same in both the gases . |
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Answer» Solution :(i) DEPENDENCE of VELOCITY of sound on density of a gas . (ii) `V alpha (1)/(sqrtd) ,d = (m)/(V)` (iii) Gas B , `V_(A)= 1.3 V_(B)` |
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| 1709. |
Afish under water observes a freely falling stone in air . If therefractive index ofwateris4/3, what is theapparent acceleration of thestone as observed by thefish? |
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Answer» Solution :(i) Let `h_(1) and h_(1)^(1)` be the real andapparent height ofthestoneat t = 0s. Let `h_(2) and h_(2)^(1)` be the real and apparent height of the STONE at t = 1 s THEREAL DISTANCE TRAVELLED ` S = h_(1) - h_(2)` Apparent distance travelled `h_(1)^(1) -h_(2)^(1) = S^(1)` ` mu = h_(1)/h_(1)^(1) ,h_(1)^(1) = h_(1)/mu and h_(2)^(1) = h_(2)/mu ` Use the relation ` s = ut + 1/2 at^(2)` In both thecases, determine theapparent acceleration. (ii) ` 13.1 ms^(-2)` |
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| 1710. |
Explain non-uniform motion. |
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Answer» Solution :If an object covers unequal distances in equal INTERVALS of time, then the object is said to be in non-uniform motion, Most of the MOTIONS, we see, in day-to-day life, are non-uniform. For example. A car is moving on a CROWDED STREET. |
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| 1711. |
Amit buys few grams of gold at the poles as per the instruction of one of his friends. He hands over the same when he meets him at the equator. Will the friend agree with the weigth of gold bought? If not, Why? Hint:The value of g is greater at the poles than at the equator.] |
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Answer» Solution :Weight DIFFERS from poles to the EQUATOR. W = m `XX` g W `INFTY` m W `infty` g at Ploes `W_(p) = m xx ` g Equator`W_(e ) = m xx g ` Weight of GOLD at equator is less than weight poles |
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| 1712. |
Are they vector of scalar quantities? Why? |
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Answer» Weight is a VECTOR quantity (POSSESS both magnitude and direction) |
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| 1713. |
Find the ratio of the effort required to raise a given load to a certain height, when the angle of inclination of a plank is changed from 60^(@) to 45^(@). Also find the lengths of the plank in the two cases given the load has tobe raised to a height of 5 m. |
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Answer» Solution :(i) RELATION between mechanical advantage (M.A.) and angle of inclination `(theta)` (ii) Load is constantand also height is constant (iii) Relate mechanical advantage to thecorrespondingtrigonometric RATIO of the angle of inclination. (vi) Also relate mechanicaladvantage to load and effort. (v) From the above two find a relation between load, effort and trigonometric ratio of the angle of inclination. (vi) Observe that the load is constant, and find theeffort in the two cases. (vii) Relate mechanicaladvantage to the length of the plane and theheight of the plane. (viii) Ratio of the efforts `= sqrt(6) : 2` LENGTHOF the PLANK in the first case = 5.773 m Length of the plank in the SECOND case = 7.07 m |
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| 1714. |
When the speed of a car moving with accelerated motion on a horizontal surface becomes four times than at the starting, then what is the change in its potential energy? |
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Answer» Would not change |
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| 1715. |
For moving train velocity-time graph is shown in the figure : (1) What is the maximum speed of the train and how long it is maintained ? (ii) What are the accelerations of the train in OA, AB and BC parts ? (ii) Find total distance travelled by the train. |
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Answer» Solution :`(i) 10 ms ^(-1) , ` till 380 s (ii)` 0.25 ms ^(-2) , 0 ms ^(-2) , - 0.125 ms ^(-2)` `(iii) 4.4 km` |
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| 1716. |
What is capillarity? |
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| 1717. |
A sound is heard 5 s later than the lightning is seen in the sky on a rainy day. Find the distance of location of lightning? Given the speed of sound 346 ms^(-1) |
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Answer» SOLUTION :SPEED = `"Distance"/"time"` Distance = speed x time =346 x 5 = 1730 m Thus, the distance of LOCATION of lightning =1730 m |
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| 1718. |
On increasing the temperature, the speed of sound in air: |
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Answer» increase |
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| 1719. |
What is the speed of the body moving with uniform acceleration at the midpoint of two points on a straight line, where the speeds are u and v respectively ? |
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Answer» SOLUTION :Let .a. be the constant acceleration and s be the distance between the two points, From equation of MOTION `v^(2) - u^(2) = `2as ............ (1) Let `v_(0)` be the speed of the body at midpoint ‘M’ of the given points. APPLYING the same equation used above, we get `v_(0)^(2) - u^(20 = 2a (s)/(2)` From (1) , we get `v_(0)^(2) - u^(2) = (v^(2) - u^(2))/(2)` `v_(0)^(2) = (v^(2) - u^(2))/(2) + u^(2)` `v_(0)^(2) = (v^(2) - u^(2) + 2u^(2))/(2)` ` v_(0) = SQRT((v^(2) + u^(2))/(2))` 
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| 1720. |
Cite an experiment to show that sound needs a material medium for its propagation. |
Answer» SOLUTION :
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| 1721. |
Which of the following statement is correct regarding velocity and speed of a moving body? |
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Answer» VELOCITY of a MOVING body is always HIGHER than its speed |
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| 1722. |
A car accelerates uniformly from 18 km h^(-1 )to 36 km h^(-1) in 5 s. Calculate (i) the acceleration and (ii) the distance covered by the car in that time. |
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Answer» Solution :Here, `u = 18 km h ^(-1) = 5 ms ^(-1)` ` v = 36 km h ^(-1) = 10 ms ^(-1)` `(i)a = (v - u)/(t)` `=(10 ms ^(-1) - 5 ms ^(-1))/( 5S)= 1 ms ^(-2)` (II) `s = ut + 1/2 at ^(2)` `= ( 5m s ^(-1)) xx (5s ) + 1/2 xx (1m s ^(-2)) xx (5s) ^(2)` `= 25 m + 12.5 m` `= 37. 5m` The acceleration of the car is `1 ms ^(-2)` and the DISTANCE covered is `37.5 m.` |
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| 1723. |
A bullet of mass 20g fired from a rifle is found to cover the distance of 30m in 4 s. Assuming that the speed of the bullet to be constant, find its kinetic energy. |
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Answer» `0.5625J` `=7.5ms^(-1)` KINETIC ENERGY, `E_(k)=(1)/(2)mv^(2)` `=(1)/(2)xx(0.02kg)(7.5ms^(-1))^(2)` `=0.5625J` |
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| 1724. |
Calculate the current flowing through a wire ofresistance 7.5 Omega connected to a battery of potentialdifference 1.5. V. |
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Answer» Solution :Given: `R = 7.5 OMEGA, V = 1.5 V` From Ohm.s law, `V = IR` CURRENT in wire `I = (V)/(R) = (1.5)/(7.5) = 0.2 A` |
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| 1725. |
Two ice skaters initially at rest, push of each other. If one skater whose mass is 60 kg has a velocity of 2m/s. What is the velocity of other skater whose mass is 40 kg ? |
| Answer» SOLUTION :3 m/s in OPPOSITE DIRCTION `(AS_(7))` | |
| 1726. |
A research team sends a sonar signal to confirm the depth of a sea. They heard an echo after 6s.Find the depth of the sea. an echo after 6s.Find the depth of the sea m/s? |
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Answer» Solution :Let the depth of the sea = d m Then Total distance TRAVELLED by SONAR signal `(s) = 2d` `=1500 m//s` Total TIME taken `(t) = 6S` From, `s= UT`, `2d=1500 m//s xx 6s` `d=9000//2 m=4.5` km |
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| 1727. |
It takes time 8 min for light to reach from the sun to the earth surface. If speed of light is taken to be 3 xx 10^8 m s^(-1), find the distance from the sun to the earth in km. |
| Answer» SOLUTION :`1.44xx10^8` KM | |
| 1728. |
Two objectsof masses 100 g and200 g are movingalong the same line and direction with velocities of 2 m/s and 1 m/s, respectively. They collide and after the collision , the first object moves at a velocity of 1.67 m /sDetermine the velocity of the second object. |
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Answer» SOLUTION :Mass of one of the objects `M_1=100 g =0.1 kg`. Mass of the other OBJECT `M_2 =200 g=0.2 kg` Velocity of `M_1` Before COLLISION `V_1 =2m//s` Velocity of `M_2` before collision ,`V_2=1 m//s` Velocity of `M_2` after collision `V_3=1.67m//s` Veloctiy of `M_2` after collision `V_4`. according to the law of conservation of momentum Total momentum before collision= Total momentum after collision Therefore `m_1v_1+m_2v_2=m_1v_3+m_2v_4` `2(0.1)+1(0.2)=1.67(0.1)+v_4(0.2)` `0.4 =0.167+0.2 v_4` `V_4 =1.165 m//s` HENCE, the velocity of the SECOND object becomes 1.165 m/s after the collision. |
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| 1730. |
State the advantages of AC over DC. |
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Answer» Solution :Advantages of AC over DC: The voltage of AC can be varied easily using a device called transformer. The AC can be CARRIED over long distances using STEP up transformers. The loss of energy while distributing current in the FORM of aC is negligible. Direct current cannot be TRANSMITTED as such. The AC can be easily converted into dC Generating AC is easier than DC. The AC can produce electromagnetic induction which is useful in several ways. |
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| 1731. |
Is it possible that displacement is greater than the distance travelled by an object ? |
| Answer» SOLUTION :No. The displacement of an object can be EQUAL to or less than the distance TRAVELLED by the object. | |
| 1732. |
An electron enters in uniform electric field with initial velocity 5 xx 10 ^(4) ms ^(-1) such that it attains the acceleration 10 ^(4) ms ^(-2)in the direction of its initial motion. (i) Calculate the necessary time required for the electron to attain the double velocity as compared to its initial velocity.(ii) How much distance the electron would cover during this interval of time? |
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Answer» SOLUTION :(II) 5s (ii) `3.75 XX 10 ^(4) ` |
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| 1734. |
A driver decreases the speed of a car from 25 ms^(-1)to 10 ms^(-1)in 5 second. Find the acceleration of the car. |
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Answer» Solution :Here, `U = 25 ms ^(-1), v =10 ms ^(-1), t = 5 s` `a = (v -u)/(t) = (10- 25 ms ^(-1))/(5s)=-3MS ^(-2).` The ACCELERATION of the car is `-3ms ^(-2).` |
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| 1735. |
Name the physical quantitiy whose SI unit is 'hertz'. Define. |
| Answer» SOLUTION :The SI unit of FREQUENCY is hertz (Hz). The number of vibrations (complete WAVES or CYCLES) produced in one second is called frequency of the wave. | |
| 1736. |
Explain why, wooden (or concrete ) sleeps are kept below the railway line . |
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| 1737. |
A car and a truck are moving with the same speed of 12ms^(-1). If their masses are in the ratio 1:5, find the ratio of their kinetic energy. |
| Answer» Solution :The RATIO of their KINETIC energy is `1:5`. (`because E_(k)propmv^(2),v` is the same). | |
| 1738. |
In stationary wave, phase difference between two particles can't be pi/3. Is this statement true or false? |
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| 1739. |
In the following example, try to identify the number of times the velocity of the ball changes. A foot ball player kicks a football to another player in his team who kicks the foot ball towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team Also identify the agent supplying the force in each case . |
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Answer» Solution :The velocity of foot ball changes four times. First when a football PLAYER KICKS to another player, second when that player kicks the football to the goal keeper. Third when the goalkeeper stops the football. Fourth when the goalkeeper kicks the football towards a player of his own team. AGENT supply the FORCE , First case - first player Seconds case - Second player Third case - Goal keeper Fourth case - Goal keeper |
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| 1740. |
Determine the refractive index of benzene if the critical angle of benzene with respect to air is 42^(@). (AS_(1)) |
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| 1741. |
An object of mass 5 kg is moving with a velocity of 10 ms ^(-1).A force is aplied so that in 20 s, it attains a velocity of 25 ms ^(-1). What is the force aplied on the object ? |
| Answer» SOLUTION :`5.75 N (AS_(1))` | |
| 1742. |
Why does a freely falling body experienceweightlessneSs? Note it down in your science diary. |
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| 1743. |
A car starting from rest accelerates uniformly to acquire a speed 20 km h^(-1) in 30 min. The distance travelled by car in this time interval will be : |
| Answer» SOLUTION :NA | |
| 1744. |
A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 ms^(-2) for 8.0 s. How far does the boat travel during this time? |
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Answer» SOLUTION :Here,` u = 0, t =8.0 s ,a = 3.0 ms ^(-2)` The DISTANCE travelled by the BOAT, `s = UT + 1/2 at ^(2)` ` = 0 xx 8 + (1)/(2) xx 3.0 ms ^(-2) (8s) ^(2) = 0 + 96 m = 96 m` The boat travels a distance of 96 m. |
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| 1745. |
A person walks distance of 4 km from his home in the north direction. Then he covers distance of 3 km in west direction. Now t from this place he direction walks toward home on the path of minimum distance between that place and home. Whatwould be the total Home distance covered by this person? |
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Answer» 5 km Hence, total distance coverd by the person `= 4 + 3 + 5 = 12 km` |
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| 1746. |
A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done same work or not? Justify your answer |
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Answer» Solution :Work is done whenever the given TWO CONDITIONS are SATISFIED: `**` A force acts on body `**` There is a displacement of the body by the application of force in or oppsite to the direction of force. When a person holds a bundle of hay over his head, then there is no displacement in the bundle of hay. Although, force of GRAVITY is ACTING on the bundle, the person is not applying any force on it. Hence in the absence of force, work done by the person on the bundle is zero. |
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| 1747. |
An object suspended from a spring balance is immersed in water filled inside an overflow jar. The water displaced by the object is collected in an empty beaker placed below the spout of the overflow jar. If the reading on the spring balance is 180" g"_(wt), then calculate the pressure exerted due to the immersion of object at the bottom of the container. Will there be any change in pressure at the lower, if the object is dropped into water ? The height of the overflow jar upto the spout is 10 cm and the area of the lower face of the block is 4" cm"^(2). |
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Answer» Solution :`"Pressure"=("Thrust")/("Area")` When the object is suspended from the spring balance, the total WEIGHT is equal to weight of the liquid inside the container + LOSS of weight. When the block is DROPPED, the pressure below the block is different. from that at other parts of the tank's BOTTOM surface. Below the block the presssure would increase corresponding to the APPARENT weight of the block. |
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| 1748. |
The velocity of sound in solid is …………… than the velocity of sound in air. |
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| 1749. |
When we stop pedaling the bicycle it stops because |
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Answer» The earths gravitational FORCE acts on it. |
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| 1750. |
Differentiate between longitudinal wave and transverse wave. |
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Answer» 1. It NEEDS medium for propogation 2. Particlesof the medium MOVE on a Direction PARALLEL to the direction of Propogation of the disturbance Ex : SOUND wave Transverse wave 1. It may or may not need medium of propogation. 2. Particles of the medium move in perpendicular direction of propogation of the disturbance Ex : light, seismic wave. |
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