A 1100-kg car is moving toward the north along a straight road at a speed of 20.
ID: 1526547 • Letter: A
Question
A 1100-kg car is moving toward the north along a straight road at a speed of 20.0m/s. The driver applies the brakes and the car comes to rest in a distance of 140m. a. If the road is completely level, what is the constant force applied to the car to bring it to rest? (Remember to secify the direction) b. If the road goes down a hill at a 4 degree angle with respect to the horizontal, what is the constant force applied to the car to bring it to rest? c. Whta is the souce of force that brings the car to rest? ( In other words, what is exerting the force on the car? ) Explain your answer clearly. Please explain fully to be rated!
Explanation / Answer
Given data
m = 1100 kg
speed, u = 20 m/s
distance, s = 140 m
Solution:
a) a = (v*v - u*u) / 2s
= ( 0 - 20*20) / (2*140)
= -1.4285
so force applied = m*a
= 1100*1.4285
= 1571.4285 N in the right direction
b) F = ma + mg sintheta
= 1571.43 + 1100*9.8*sin 4
= 2323.4 N
c) The road applies the stopping force to the tires, when the brakes are applied and wheels do not turn freely.
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