Question

Give an example of a situation in which there is a force and a displacement, but the force does no work. Explain why it does no work.

Short answer

The work done by gravity on the girl during a horizontal displacement is zero since the weight is perpendicular to the displacement and the cosine of 90 degrees is zero.

Step-by-step solution

Understanding Work and Energy.

Transferring energy into an object to cause some displacement is what is referred to as work. Energy is characterised as the capacity for work.

Physical work is a scalar that connects the force vector and the displacement vector, two vector quantities. For instance, the force F of an expanding gas propelling a piston along a distance D inside a tube.

Example.

Think of a woman skating on a horizontal track at a given pace. Weight-wise, the female is always vertically downward and parallel to the displacement. The weight or gravitational force is ineffective in this situation.

The work W performed by a constant force F is equal to the product of the magnitude of the vector F, the magnitude of the displacement vector D, and the cosine of the angle between F and D. (such as weight).

$W=FD\cos \theta$

Conclusion.

We can infer that no work is done on the girl by gravity during a horizontal displacement because the weight is perpendicular to the displacement and the cosine of 90 degrees is zero.