rotational motion

Question

 Suppose you start an antique car by exerting a force of 290 N on its crank for 0.13 s.

f = 290 N

t = 0.13 s

d = 0.38 m

What angular momentum is given to the engine if the handle of the crank is 0.38 m from the pivot and the force is exerted to create maximum torque the entire time?

Answer 1

Putting the problem into rotational terms: τ = Fl = (290N)(.38m) = 110.2 Nm

You are given that t = .13 seconds and L, the angular momentum, is the unknown.

By analogy with the impulse equation: FΔt = Δp, you write τΔt = ΔL for angular impulse.

Now just substitute into L(t) - 0 = τΔt