the awnser to ur question is D
Running on sand requires 1.6 times more energy spent than running on hard surface, so the force applied by our foot on sand is less.
Here stress is parallel to the surface of the body. So it's a Shear stress.
The ratio of the distance moved by the point at which the effort is applied in a simple machine to the distance moved by the point at which the load is applied, in the same time. In the case of an ideal (frictionless and weightless) machine, velocity ratio = mechanical advantage. Velocity ratio is sometimes called distance ratio.
