How does the atmospheric pressure change with altitude?

Find the moment of force of 20 N about an axis of rotation at a distance of 0.5 m from the force.

A spanner of length 10 cm is used to unscrew a nut by applying a minimum force of 5.0 N. Calculate the moment of force required.

A wheel of diameter 2 m can be rotated about an axis passing through its centre by a moment of force equal to 2.0 N m. What minimum force must be applied on its rim?