Question

Which of the following is (are) true?

1. When an object strikes a stationary object of equal mass, momentum of each object is separately conserved

2. Objects with the same velocity always have the same momentum

3. You are standing at rest on a horizontal frictionless floor. You might get yourself moving by throwing a shoe horizontally

A. 1 and 3 only

B. 2 and 3 only

C. 1 and 2 only

D. 2 only

E. 3 only

Answer 1

3 only is correct .

1) Momentum of the system is conserved not individual bodies . Hence Wrong

2) object may have same velocity but if masses are different the momentum is also different . P = mv . Hence wrong .

3) since the floor is frictionless there is no external force on the system in horizontal direction hence if a shoe is thrown horizontally forward he will experience an impulse horizontally backward. Hence right .