Question

A body of mass m is moved from the ground to a height h. If force of gravity on mass of 1 kg is newton find the force needed to lift the body.​

Answer 1

Answer

• Force = g N

Given

A body of mass m is moved from the ground to a height h. If force of gravity on mass of 1 kg is newton

To Find

The force needed to lift the body

Solution

Mass , m = 1 kg

Force , F = ? N

Acceleration due to gravity , a = g

Now , " Force is defined as product of mass and acceleration "

⇒ F = ma

⇒ F = mg

So , this force is equals to weight of the body.

⇒ F = (1) g

⇒ F = g N

So , Force needed to lift the body is equals to acceleration due to gravity .

Answer 2

CORRECT QUESTION:

A body of mass m is moved from ground to a height h. If force of gravity on mass of 1 kg is g newton. Find the force needed to lift the body?

ANSWER:

• Force on m kg = mg

GIVEN:

• A body of mass m is moved from ground to a height h.

• Force of gravity on mass of 1 kg is g newton.

EXPLANATION:

Force on 1 kg -------> g N

Force on m kg ------> x N

x = m × g / 1

x = mg N

Force on m kg body = mg N [ Here g means force due to the gravity ]

ADDITIONAL POINTS:

Force = ma [where m = mass and a = acceleration]

work done = F × d [ F = mg, h = h ]

work done = mg × h

work done = change in Potential energy

When h = 0 , work done = mg × 0 = 0

When it is lifted to height h, work done = mgh

Hence change in potential energy = U - U' = mgh - 0 = mgh

[ Here U = final potential energy and U' = initial potential energy ]