A 6 N force and a 15 N force act on an object. The moment arm of the 6 N force is 0.4 m. If the 15 N 20. force provides 5 times the torque of the 6 N force, what is its moment arm?

0.8 m

Explanation:

For "6 N" force:

F = magnitude of the force = 6 N

r = moment arm = 0.4 m

Torque due to "6 N" force is given as

τ = r F

τ = (0.4) (6)

τ = 2.4 Nm

For " 15 N" force:

F' = magnitude of the force = 15 N

r' = moment arm = ?

τ' = Torque = 5 τ = 5 x 2.4 = 12 Nm

Torque due to "15 N" force is given as

τ' = r' F'

12 = r' (15)

r' = 0.8 m

So the moment arm for "15 N" force is 0.8 m