A piece of putty moving with 2 units of momentum strikes and sticks to a heavy bowling ball that is initially at rest. After the putty sticks to the ball, both are set in motion with a combined momentum that is:.
a) less than 2 units.
b) 2 units.
c) more than 2 units.

The combined momentum will be 2 units.

Explanation:

Here a piece of putty moving with 2 units of momentum strikes and sticks to a heavy bowling ball that is initially at rest. After the putty sticks to the ball, both are set in motion with a combined momentum. It is a case of inelastic collision in which the momentum of the system remains conserved.

The law of conservation of momentum will be followed here. So, the combined momentum after collision will be same as the initial momentum. Hence, the correct option is (b) "2 units".

not too sure thinking all accelerations are pointed down

it is b. absorbs thermal energy