Imagine that the car in example N3.5 must convert chemical energy to other forms
ID: 2142716 • Letter: I
Question
Imagine that the car in example N3.5 must convert chemical energy to other forms at a rate of 40 kW to keep moving at a constant speed. If the car's mass is m = 1450 kg, its constant speed is v = 35 m/s, and the radius of the curve is R = 150 m, what angle does the static friction force on the car make with the car's direction of travel as it rounds the curve? Be sure to describe your reasoning. (Hint: Argue that the rate at which drag extracts energy from the car's kinetic energy is given by [dk]/[dt] = F*v = -F*v. )
Explanation / Answer
power = F*v
40,000 = F*35
F = 1142.85 N
friction force = ?1142.5
dk/dt =
2mvdv/dt
=2mv(?N/m)
so 2v?N = 40000
2*35*?*1142.5 = 40000
? = 0.5