In the Soapbox Derby, young participants build non-motorized cars with very low-
ID: 1275618 • Letter: I
Question
In the Soapbox Derby, young participants build non-motorized cars with very low-friction wheels. Cars race by rolling down a hill. Assume that the track begins with a 63-ft-long (1 m = 3.28 ft) section tilted 15? below horizontal.
Part A
What is the maximum possible acceleration of a car moving down this stretch of track?
Express your answer to two significant figures and include the appropriate units.
Part B
If a car starts from rest and undergoes this acceleration for the full l, what is its final speed in m/s?
Express your answer using two significant figures.
Explanation / Answer
F(net) = F(gravity)
m * a(max) = mg * sin15
a(max) = 9.8 * 0.22
= 2.54 m/s2
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v2 = u2 + 2as
v2 = 0 + 2 x 2.54 x 19.2
v = 9.88 m/s