An object with a mass of #18 kg# is hanging from an axle with a radius of #16 cm#. If the wheel attached to the axle has a radius of #28 cm#, how much force must be applied to the wheel to keep the object from falling?
Force on wheel = 100.8N (in opposite direction)
force due to gravity s 9.8N/kg (=176.4N for 18kg object)
turning moment is force*radius
remember to convert to standard units (metres, Newtons, etc.)
object's turning moment (a.k.a. torque) will be :
to prevent the axle turning the sum of the moments must be zero
the negative value means the force is applied in the opposite direction to that due to the object