Question

Calculate the height through which a body of mass 40 kg can be lifted when 800J of
work is done on it. Take g=10 ms‐2​

Answer 1

Given :-

◉ A body of mass m = 40 Kg

◉ Work to be done, W = 800 J

g = 10 m/s²

To Find :-

◉ Height at which the body have to be raised providing the work done to be 800 joule.

Solution :-

We know, On the ground at time = 0 s, The potential energy of the body would be 0 joule.

When It is raised to a certain height, say h, The total energy (Kinetic energy) at the beginning of the journey would be converted into Potential energy.

Hence, The work done is 800 joule, So the potential energy would be 800 joule at h.

Further,

⇒ Potential energy = mgh

Where,

• m = mass of body
• g = acceleration due to gravity
• h = height

⇒ 40 × 10 × h = 800 (given)

⇒ 400h = 800

⇒ h = 2 m

Hence, The body would be raised to 2 meters above the surface providing the work done to be 800 joule.

Some Information :-

◉ Because of the law of conservation of energy, the potential energy of a body at height h is equal to the kinetic energy of the body before hitting the ground.

◉ Kinetic energy = 1/2 mv²

Where,

• m = Mass of Body
• v = Velocity of body

Answer 2

Answer:

Explanation:

Given that,

Calculate the height through which a body of mass 40 kg can be lifted when 800 J of work is done on it. Take g = 10ms-².

Solution:

We have,

Mass(m) = 40kg

Acceleration due to gravity (g) = 10m/s-²

Height (h) = ?

Here,

Potential energy is work done(800J).

So,

P.E = mgh

800J = 40 × 10 × h

h = 800/400

h = 80/40

h = 8/4

h = 2m.

Therefore, height is 2m.

Hence proved,

The height through which a body of mass 40 kg can be lifted when 800J is 2m.

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