How to Calculate Momentum and Find Forces in a Collision?

[Messiah19]

Homework Statement

2:

A car of mass 1000kg moving with a speed of 10m/s has head on collision with a truck of mass 2000kg moving in the opposite direction with a speed of 5m/s. After impact the car moves with a speed of 2m/s in the opposite direction to its original motion.

1 Calculate the rate of change of momentum of the car if the impact lasts for 0.25 sec

2 what is the force that the car exerts on the truck during impact. State the laws.

3 Find the velocity of the truck after collision

Homework Equations

No equations given

The Attempt at a Solution

1: Mv- Mu
1000 * 10 - 1000* -2 = 12000/0.25 = 48 000 N

2: For every action there is an equal and opposite reaction so 48000 N

3: don't have a clue :(

 

[quantumdude]

Homework Equations

No equations given

Yes there are. Look up "conservation of momentum" and "impulse".

The Attempt at a Solution

1: Mv- Mu
1000 * 10 - 1000* -2 = 12000/0.25 = 48 000 N

You've got the units wrong. If you multiply mass times velocity, you get a momentum, not a force. But even after correcting that, it gives you the change $\Delta p$ in momentum. You were asked for the rate of change $\Delta p / \Delta t$ of the momentum.

2: For every action there is an equal and opposite reaction so 48000 N

Again, look up "impulse" in your book.

3: don't have a clue :(

For this one, look up "conservation of momentum" in your book.

Try to implement my advice in another solution attempt. If you're still stuck, then repost.