James Stewart, 2002 Motorcross/Supercross Rookie of the Year, is leading a race when he runs out of gas near the finish line. He is moving at 16 m/s when he enters a section of the course covered with sand where the effective coefficient of friction is 0.90. Will he be able to coast through this 15-m-long section to the finish line at the end? If yes, What is his speed at the finish line?

Question

Beckham

Physics

27 July, 21:09

James Stewart, 2002 Motorcross/Supercross Rookie of the Year, is leading a race when he runs out of gas near the finish line. He is moving at 16 m/s when he enters a section of the course covered with sand where the effective coefficient of friction is 0.90. Will he be able to coast through this 15-m-long section to the finish line at the end? If yes, What is his speed at the finish line?

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Quinton Meyer · Answer 1

We are given the coefficient of friction which is:

Cf = 0.90

The acceleration based on this would be:

a = - Cf * g

a = - 0.90 * (9.81 m/s^2)

a = - 8.83 m/s^2

Calculate the distance at his total stop v = 0 using the formula:

v^2 = vo^2 + 2ad

where v is final velocity = 0, vo is initial velocity = 16, d is distance

0 = 16^2 + 2 (-8.83) d

d = 14.5 m

So he is short by 0.5 m, he does not reach the finish line