## Center of Mass, Momentum and Collision JEE MAIN QUIZ

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- Question 1 of 15
##### 1. Question

4 pointsA man weighing 80 kg is standing at the center of a flat boat and he is 20 m away from the shore. He walks 8 m on the boat towards the shore and then halts. The boat weight is 200 kg. How far is he from the shore at the end of this time:

CorrectIncorrect - Question 2 of 15
##### 2. Question

4 pointsA non-zero external force acts on a system of particles. The velocity and acceleration of the center of mass are found to be ‘v’ and ‘a’ respectively at any instant. It is impossible that

(1) v=0,a=0 (2)v≠0,a=0 (3)v=0,a≠0 (4)v≠0,a≠0

Then:

CorrectIncorrect - Question 3 of 15
##### 3. Question

4 pointsA boy hits a baseballl with a bat and imparts an impulse ?J to the ball. The boy hits the ball again with the same force, except that the ball and the bat are in contact for twice the amount of time as in the first hit. The new impulse equals:

CorrectIncorrect - Question 4 of 15
##### 4. Question

4 pointsTwo balls of same mass are dropped from the same height h, on to the floor. The first ball bounces to a height h/4 after the collision and the second ball to a height h/16. The impulse applied by the 1st ball and the second ball on the ground are A and B respectively. Then :

CorrectIncorrect - Question 5 of 15
##### 5. Question

4 pointsBall A of mass 5 kg moving at 20 m/s collides with ball B of unknown mass moving at 10 m/s in the same direction. After the collision, ball A moves at 10 m/s and ball B moves at 15 m/s, both still in the same direction. What is the mass of ball B:

CorrectIncorrect - Question 6 of 15
##### 6. Question

4 pointsA smooth small spherical ball of mass m, moving with velocity u collides head on with another small spherical ball of mass 3m, which was at rest initially. 2/3 rd of the initial kinetic energy of the system is lost. The coefficient of restitution between the balls is:

CorrectIncorrect - Question 7 of 15
##### 7. Question

4 pointsA ball is projected from ground with a velocity V at an angle Φ to the vertical. On its path it makes an elastic collision with a vertical wall and returns to ground. The total time of flight of ball is:

CorrectIncorrect - Question 8 of 15
##### 8. Question

4 pointsA ball strikes a smooth horizontal ground at an angle of 45° with the vertical. What cannot be the possible angle of its velocity with the vertical after the collision. (Assume e≤1).

CorrectIncorrect - Question 9 of 15
##### 9. Question

4 pointsA ball is thrown downwards with initial speed = 6 m/s, from a point at height = 3.2 m above horizontal floor. If the ball rebounds back to the same height then the coefficient of restitution equals to:

CorrectIncorrect - Question 10 of 15
##### 10. Question

4 pointsA ball of mass 1 kg strikes a heavy platform, elastically, moving upwards with a velocity of 5 m/s. The speed of the ball just before the collision is 10 m/s downwards. Then the impulse imparted by the platform on the ball is:

CorrectIncorrect - Question 11 of 15
##### 11. Question

4 pointsA mass ‘m’ with a velocity ‘v’ and collides inelastically with another identical mass at rest. After collision the 1st mass moves with velocity v/√3 in a direction perpendicular to the initial direction of motion. Find the speed of the 2nd mass after the collision:

CorrectIncorrect - Question 12 of 15
##### 12. Question

4 pointsAn open water tight railway wagon of mass 5000 kg coasts at an initial velocity 1.2 m/s without friction on a railway track. Rain drops fall vertically downwards into the wagon. The velocity of the wagon after it has collected 1000 kg water will be :

CorrectIncorrect - Question 13 of 15
##### 13. Question

4 pointsAn isolated particle of mass m is moving in horizontal plane (x-y), along the x – axis, at a certain height above the ground. It suddenly explodes into two fragments of m/4 and 3m/4. An instant later, the smaller fragment is at y = +15 cm. The larger fragment at this instant is at :-

CorrectIncorrect - Question 14 of 15
##### 14. Question

4 pointsA block of mass 0.5 kg is moving with a speed of 2 m/s on a smooth surface. It strikes another block of mass 1 kg and then they stick together to form a single body. The loss of energy during this collision is:

CorrectIncorrect - Question 15 of 15
##### 15. Question

4 pointsA circular disc of radius R is removed from a bigger circular disc of radius 2 R such that the circumference of the discs coincide. The center of mass of the new disk is ‘k’ R from the center of the bigger disc. The value of ‘k’ is :-

CorrectIncorrect