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# conservation of momentum.

Posted on 2003-11-07

Hi,

I am looking through past Physics exam papers and I am having trouble understanding a question. Here it is.

"Jack and Jill are racing their toboggans down an icy hill. Jack and Jill are of similar mass and are using the same type of toboggan. When Jack is a certain distance from the end of the race they are travelling with the same velocity. Jack is behind Jill and decides that if he is going to win the race he must lighten his toboggan, so he pushes a box containing their ice-skating gear off the side of his toboggan.

Explain, giving clear reasons, whether this will be a successful way for Jack to catch up to Jill and help him win the race"

The solutions to the exam say that "this question could have been answered using a conservation of momentum approach or by application of Newton's Second Law ....."

Firstly could someone please tell me what the Newton's second law states. Isn't the rule for conservation of momentium m1*u1 + m2*u2 = -m1*v1+m2*v2

where m = mass

u=init velocity

v=final velocity

I am not sure how this idea could be used to explain the situation. Could someone please help. I realise that the mass won't increase or decrease acceleration, but I have to prove it using the methods described in the solutions (stated above)

Thanks in advance.