Answer:
From question (a) and (b) the pendulum motion is perpendicular to the force so the normal force will do no work and the tension in the string of the pendulum will not work

And
so

c
An example will be a where a stone is attached to the end of a string and is made to move in a circular motion while keeping the other end of the string in a fixed position
d
A dog walking along a surface which has friction, here the frictional force would acting in the direction of the motion and this would do positive work
Explanation:
Hydro then electric or solar power
Formed from an object blocking the light to a certain area.
Is not always the same size or shape, it varies depending on the position of the light.
You can have more than one shadow of you have more than one light source.

For displacement apply Pythagorean theorem


