Emily W. answered • 05/14/22
B.S. in Physics with 7+ years Experience
Suppose you start an antique car by exerting a force of 290 N on its crank for 0.13 s.
F = 290N
t = 0.13 seconds
d = 0.38m
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?
Angular Momentum L = mvr
J Impulse = change in linear momentum = F*t = m* delta v
To create maximum torque we are assuming that the force is being applied perpendicular to the lever arm because only the part of the force that is perpendicular to the radius will create rotation.
J = (290)(0.13) = 37.7 N*s
convert from linear to angular —> times by radius of rotation (distance from pivot to force)
change in angular momentum = 37.7 * 0.38 = 14.33 kgm^2/s
If angular momentum L started at 0 (not moving) then the final angular momentum is
L final = L initial + L change
L final = 0 + 14.33
L final = 14.33 kgm^2/s
