Momentum problems

Question

1.A 1,544 kg car moving at 27.1 m/s hits a stationary truck with a mass of 3,174 kg. If the two vehicles become stuck together in the collision, how fast do they move away from the point of impact?

2.A 51 kg girl rides on a 3.2 kg skateboard. The girl on the skateboard moves at 1.1 m/s. If the girl jumps off the skateboard backwards with a velocity of 1.9 m/s, how fast does the skateboard roll away?

3.A 0.042 kg bullet moving at 472 m/s strikes a stationary 2.8 kg wooden block. The bullet passes through the block and leaves with a velocity of 253 m/s. If the block was originally at rest, how fast does it move after being hit by the bullet?

*answer and explanation please*

Answer 1

I gave a general answer here:

https://www.wyzant.com/resources/answers/729352/momentum-and-impulse-problems

Did you read that and understand it?

Let's look at the first problem:

1.A 1,544 kg car moving at 27.1 m/s hits a stationary truck with a mass of 3,174 kg. If the two vehicles become stuck together in the collision, how fast do they move away from the point of impact?

The initial momentum is m1*v1= 1544 * 27.1.

The momentum after the impact must be the same......

After the impact, the total mass is 1544 + 3174, and the momentum is (1544 + 3174)*v2

Since the initial and final momentum must be the same, we can now write:

(1544 + 3174)*v2 = 1544 * 27.1

Solve this for v2

You will use a similar method to solve the other problems