Posted by **Will** on Friday, January 6, 2012 at 9:30pm.

A 1000 kg car is moving at a constant speed of 7 m/s when it hits the back bumper of another car with 1200 kg of mass moving in the same direction at a constant speed of 6 m/s. As a result of the collision both bumpers get coupled. Show all work and calculations.

1. What is the combined mass of both cars?

2. What is the combined weight of both cars?

3. What is the total momentum of the system before and after the collision?

4. What is the speed of both cars after the collision?

5. What is the combined kinetic energy of both cars after the collision?

- Physics -
**drwls**, Friday, January 6, 2012 at 11:48pm
Aren't you able to do any of this yourself? Can you add the masses of the two cars?

Do you know how to compute weight from mass?

Use the definition of momentum for part 3.

Use conservation of momentum for part 4.

Use the definition of kinetic energy and the result of 4. for part 5.

Show your work if further help is needed.

- Physics -
**Will**, Saturday, January 7, 2012 at 8:40am
Sorry, I can do part 1 and 2 relatively easily. However, I suck at physics and was honestly hoping to receive an answer like the one you gave me. I just wanted to know how to do it, not necessarily get the answer. Thanks

- Physics -
**Will**, Saturday, January 7, 2012 at 3:19pm
Ok Here are my answers, if you can give me any more help it would be greatly appreciated.

1. 1000+1200=2200

2. Fw = ma

1000*9.8 m/s^2 = 9800

1200*9.8 m/s^2 = 11760

Fw = 21,560

3. Momentum = mv

1000*7 + 1200*6

7000 + 7200

Momentum = 14,200 kg m/s

4. 14,200 / m1+m2

14,200 / 1000+1200

14,200 / 2200

speed after collision = 6.5

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