Biomechanics

Frictional forces within liquids are lower than within solids. Sliding friction IS less than static friction.

Choice B is almost correct, but the unit of force is the newton, while the kilogram is the unit of mass.

Weight is a force. It is the attractive force between the Earth’s mass and the object’s mass.

Minimising friction will both minimise the muscular effort (force) required and also the shearing force on the patient’s skin.

When the muscle insertion is closer to the joint than is the load, the effort arm is short. This means that the effort force must be large to provide the same torque exerted by the load acting on its longer load arm.

Bending the legs at the knees (and hips) allows the strong thigh muscles to be used to extend the legs while rising to a standing position with the load.

This strategy will keep the load arms of the levers as short as possible. In addition adopt a wide base of support, bend your knees and use your leg muscles to lift.

It is best to keep the feet separated to widen the base of support. A wide stance also makes it easier to get close to the object to be lifted.

The closer is the effort to the fulcrum, the greater is the effort it must exert to shift the load.

As the force is balanced, there is no net force acting in any direction, so there is no change in motion.