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In the Soapbox Derby in (Figure 1), young participants build non-motorized cars

ID: 1523299 • Letter: I

Question

In the Soapbox Derby in (Figure 1), 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 14 degree below horizontal. 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. 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

Given inclination theta = 14

length l = 63 ft = 63 * (1/3.28) m

l = 19.2 m

when the car roll down the hill with very low friction

the componentof weight ( m * g * sin(theta) acts along the inclinition

a) the maximum possible acceleration is

a = g * sin(theta)

a = 9.8 * sin(14)

a = 2.37 m/s^2

b)

here initial velocity u = 0

final velocity v = ?

acceleration a = 2.37 m/s^2

from v^2 - u^2 = 2 * a * l

v^2 - 0 = 2 * 2.37 * 19.2

v = 9.54 m/s