You are driving a long, thinking about a difficult physics problem, and you fail

Question

You are driving a long, thinking about a difficult physics problem, and you fail to notice the warning lights at the entrance to a drawbridge. you stop with your rear bumper 6.0 m beyond the gate that descends behind your car. As you sit with your brakes locked the bridge begins to open. When the bridge reaches an agle of 45 deg., your car begins to slide backwards and strikes the gate, causing considerable damage. (a) What is the coefficient of static friction between your tires and the bridge? (b) how fast were you going when you struck the bridge? (c) what action could you have taken after the bridge opened that would have reduced the damage? Explain

Explanation / Answer

a) so mg sin theta - friction = 0

mg sin theta - u m g cos theta = 0

u = tan theta = tan(45) = 1

b) conservation of energy

m g h = 1/2 mv^2

v = sqrt(2 g h) = sqrt(2*9.81*6.0*sin(45) )= 9.12 m/s

c) used your brakes to increase friction

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.