A glob of sticky putty is thrown against a slightly open door so that it sticks on impact and gives the door a momentum of 1.4 kg m/s. A rubber ball with exactly the same mass and velocity as the sticky putty strikes the door and bounces back at its initial speed in the opposite direction. What impulse does it impart to the door?

2.8 kgm/s

1.4 kgm/s

0.70 kgm/s

0 kgm/s

Question

A glob of sticky putty is thrown against a slightly open door so that it sticks on impact and gives the door a momentum of 1.4 kg m/s. A rubber ball with exactly the same mass and velocity as the sticky putty strikes the door and bounces back at its initial speed in the opposite direction. What impulse does it impart to the door?

       2.8 kgm/s

       1.4 kgm/s

       0.70 kgm/s

       0 kgm/s

anonymous · Answer

0 If the ball has the same mass and velocity as the sticky putty then it hits the door and imparts the same momentum and you can assume conservation of momentum and say the door imparts that momentum back to the ball as it bounce back off the door so the net momentum change is 0.

anonymous · Answer

Okay, Thanks. I thought the answer was zero, but I wanted to make sure.