Question

An object of mass 2 kg is kept on a table of height 1 m. How much work
is required to be done on the object to raise its height to 4m vertically
upwards?

Answer 1

Given:-

• Mass ,m = 2 kg

• Height of table ,h1 = 1 m

• Height of object when raised ,h2 = 4m

• Acceleration due to gravity ,g = 9.8m/s²

To Find:-

• Work Done ,W

Solution:-

Firstly we calculate the height raise by object from table.

h = h2-h1

→ h = 4-1 = 3m

We have to calculate the work done against gravity.

• W = mgh

Where,

W is the work done

m is the mass

g is the acceleration due to gravity

h is the height

Substitute the value we get

→ W = 2×9.8×3

→ W = 19.6 × 3

→ W = 58.8 ≈ 59 J

Therefore,the work done on the object to raise its height is 59 Joules.

Answer 2

Given:

Mass = 2 kg

Height of table = 1 m

Height till which the object is raised = 4 m

To find:

Work done to raise the object till 4 m height

Solution:

Potential Energy at 4 m:-

E = mgh

→ E = 2(10)(4)

→ E = 80 J

Potential Energy at 1 m:-

E = mgh

→ E = 2(10)(1)

→ E = 20 J

∆E = Work Done

→ $\boxed{\sf{ Work \: Done = 60 J}}$