Question

Suppose you start an antique car by exerting a force of 300 N on its crank for 0.250 s. What angular momentum is given to the engine if the handle of the crank is 0.300 m from the pivot and the force is exerted to create maximum torque the entire time?

Answer 1

Answer

given,

Force on car, F = 300 N

time, t = 0.250 s

distance of the force from the pivot, r= 0.3 m

Angular momentum = ?

Now,

torque acting is calculated by multiplying force with displacement.

    $\tau = F \times r$

    $\tau = 300 \times 0.3$

    $\tau = 90\ N.m$

we know,

torque is equal to change in angular momentum per unit time.

$\tau = \dfrac{\Delta L}{\Delta t}$

Δ L = τ Δ t

initial angular  momentum is zero

L = 90 x 0.25

L = 22.5 kg.m²/s

Angular momentum is equal to 22.5 kg.m²/s