Question

Q. 20 An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground The initial and final points of object lie on the same horizontal line. What is the work
done by the force of gravity on the object?​

Answer 1

Since the initial and final points of the path of an object thrown at certain angle to the ground lie on the same horizontal line, the displacement of the object is only in the horizontal direction. Since there is no net displacement of the object in the vertical direction ,therefore, no work done by the force of gravity on the object.

Answer 2

Explanation:

Work is done when force applied produce motion in the direction of the force.

In this case :-

But the displacement of the body is the horizontal direction.

Since, angle between force and displacement is 90°.

Now, the work done is 0 as the initial and final velocity are on the same path so the height will be 0.

Force is applied in the vertical direction.

We know that,

★ W = m × g × h ★

where,

Work = Work Done

m = Mass

g = Gravity

h = Height

⇒ W = m × g × h

⇒ W = m × g × 0

➠ W = 0 J