55. A 2 kg block slides on a horizontal floorwith a speed of 4m/s. It

1.	55. A 2 kg block slides on a horizontal floorwith a speed of 4m/s. It strikes auncompressed spring, and compresses ittill the block is motionless. The kineticfriction force is 15 N and spring constantis 10,000N/m. The spring is compressedby:(A) 8.5 cm(B) 5.5 cm(C) 2.5 cm(D) 11.0 cnm
Answer» As the block is moving with some initial velocity it must be having must KE. Finally it comes to rest so kinetic energy final will be zero.. it ll have some potential energy. As frictional force is also given it will some work done by friction.. applyling the work energy theorm... Work done(external force) + work done (non conservative force ) = change in kinkinetic energy+ change in potential energy. 0 + 15x = kf - ki + pf - pi. 0 + 15x = 0 + 1/2mv2 + k/2x² - 0. On putting the values you get a qquadric equation i.e, 5000x² - 15x -16=0 solving this equation x = 0.056m or 5.6 cm hence, option (b) is correct

55. A 2 kg block slides on a horizontal floorwith a speed of 4m/s. It strikes auncompressed spring, and compresses ittill the block is motionless. The kineticfriction force is 15 N and spring constantis 10,000N/m. The spring is compressedby:(A) 8.5 cm(B) 5.5 cm(C) 2.5 cm(D) 11.0 cnm

Answer»

As the block is moving with some initial velocity it must be having must KE.

Finally it comes to rest so kinetic energy final will be zero.. it ll have some potential energy.

As frictional force is also given it will some work done by friction.. applyling the work energy theorm...

Work done(external force) + work done (non conservative force ) = change in kinkinetic energy+ change in potential energy.

0 + 15x = kf - ki + pf - pi. 0 + 15x = 0 + 1/2mv2 + k/2x² - 0.

On putting the values you get a qquadric equation i.e, 5000x² - 15x -16=0 solving this equation

x = 0.056m or 5.6 cm

hence, option (b) is correct

Discussion

No Comment Found

Related InterviewSolutions

7. A body has a weight 50 N in air. Afterimmersing completely in liquid its weight is20 N. Then, the buoyant force on the bodywill be
Name the particulate which causes the disease mentioned below:(a)minamata (b)silicosis.
- Where does a body weight more at the surface of the carth or in a mine?
DelyAbody79entire chainthe ch.57. A body of mass 50gm collides elastically with anotherbody of mass 30 gm at rest. Then the percentage lossof the velocity of the colliding body during collision is1) 25% 2) 75% 3) 50% 4) 67%3) 120380.beide
What will be the acceleration of a body of mass5 kg if a force of 200 N is applied on it?
Rig. 5.168.13 Two bodles of masses 10 kg and 20 kg respectively kept on a smooth, hortzontalsurface are tied to the ends of a light string a horizontal force F 600 Nsapplied to lu A (t) B along the direction of string. What is the tension in thestring in each case
culate the gravitational force befween two protons kept at a distance67 x 10-27 kg. (1 femtometre = 10-15 m)
15. A uniform chain of length 2 m is kept on atable such that a length of 60 cm hangs freelyfrom the edge of the table. The total mass ofthe chain is 4 kg. What is the work done inpulling the entire chain onto the table ?(g = 10 m/s)1) 7.2J273.63) 120J4) 1200
Two block of mass 3 kg and 6 kg respectively are placed on a smooth 1.0 m/shorizontal surface. They are connected by a light spring of force 3 kgconstant k 200 N/m. Initially the spring is unstretched. The indicatedzmvelocities are imparted to the blocks. The maximum extension of thespring will be:A30 cm(C) 20 cm2.0 mls(B) 25 cm(D) 15 cm
88. A piece of stone is thrown vertically upwards. It reaches the maximum height in 3 seconds. If the accelerationof the stone be 9.8 m/s directed towards the ground, calculate the initial velocity of the stone with which itis thrown upwards.