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# Im stuck! watch

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1. Hi,

Can someone pls help me out with these momentum Q's?? I'm really lost

[1] A kitten of mass 0.60kg leaps at 30 degrees to the horizontal out of a toy truck of mass 1.2kg causing it to move over horizontal ground at 4 m/s. At what aped did the kitten leap?

[2] A particle of mass 5m moving with speed v explodes & splits into two pieces with masses of 2m & 3m. The lighter piece continues to move in the original direction with a speed of 5v relative to the heavier piece. What is the actual speed of the lighter piece?

I dont want the answers-just explanation pls! I'll be really grateful
2. (Original post by hira89)
Hi,

Can someone pls help me out with these momentum Q's?? I'm really lost

[1] A kitten of mass 0.60kg leaps at 30 degrees to the horizontal out of a toy truck of mass 1.2kg causing it to move over horizontal ground at 4 m/s. At what aped did the kitten leap?

[2] A particle of mass 5m moving with speed v explodes & splits into two pieces with masses of 2m & 3m. The lighter piece continues to move in the original direction with a speed of 5v relative to the heavier piece. What is the actual speed of the lighter piece?

I dont want the answers-just explanation pls! I'll be really grateful
Conservation of Momentum.
When you have a system momentum is always the same. Even after an event (ie an explosion or a kitten jumping out).
So at the start momentum is
(mass of object 1 and 2)(velocity of objects)
After it is
(mass of object 1)(velocity of object 1) + (mass of object 2)(velocity of object 2)
Note velocities may be negative, in fact in most momentum questions at least one of the objects has negative momentum.
The point is to fiddle the numbers so that the two lines equal.
3. but initially the toy truck (with the kitten) is at rest...so there's no momentum value?
4. (Original post by hira89)
but initially the toy truck (with the kitten) is at rest...so there's no momentum value?
Yes, the momentum will be 0.
5. OK, so then that means the final momentum should be zero too right?
6. (Original post by hira89)
OK, so then that means the final momentum should be zero too right?
correct. The total [horizontal] final momentum = 0
7. Just joined and spotted this one. Sorry if it's a bit late now!
You need to remember that momentum will add up to zero because velocity needs direction i.e. if you consider moving to the right as being positive and to the left as negative, when you find your momentum values and add them - together they'll equal zero.

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