Author Topic: Help with a Momentum and/or work energy problem (Read 544 times) Tweet Share

jujimufu · « **on:** March 11, 2010, 04:33:54 pm »

Two Friends on roller-blades push apart from each other in opposite direction. Geri of mass 50 kg rolls 15m before stopping. Friend Nina has mass 40kg: how far does Nina travel before stopping? Assume that they experience the same frictional force along their past (NB. during the time they are pushing each other the effect of the frictional force is negligible) Hint: think momentum and work energy

Help will be much appreciated

/0 · « **Reply #1 on:** March 11, 2010, 04:59:08 pm »

Let Geri's initial Kinetic Energy be $\frac{1}{2}m_Gv^2$ .

Then $\frac{1}{2}m_Gv^2 - F_{fr}x=0$ .

$\Rightarrow \frac{1}{2}(50)v^2 = F_{fr}(15)$

$\Rightarrow F_{fr} = \frac{5}{3}v^2$

Now look at Nina's kinetic energy

methodsman · « **Reply #2 on:** March 12, 2010, 10:51:41 pm »

Isn't this from physics unit 3 (motion)?

superflya · « **Reply #3 on:** March 12, 2010, 10:53:38 pm »

Quote from: methodsman on March 12, 2010, 10:51:41 pm

Isn't this from physics unit 3 (motion)?

yea :S

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Author Topic: Help with a Momentum and/or work energy problem (Read 544 times) Tweet Share

jujimufu

Help with a Momentum and/or work energy problem

/0

Re: Help with a Momentum and/or work energy problem

methodsman

Re: Help with a Momentum and/or work energy problem

superflya

Re: Help with a Momentum and/or work energy problem

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