Question

A body of mass 5kg is lifted vertically at a constant velocity of 12m. Calculate a) the force applied b) work done in lifting the body c) what happens to the work performed ? Class 9th Worksheet physics chapter4 work and energy.

Answer 1

Answer:

a) Given, mass, m = 5 kg

acceleration due to gravity, g = 9.8 m/s²

We know, F = mg

= 5×9.8 N

= 49 N

b) Given, mass, m = 5 kg

velocity, v = 12 m/s

We know, W = Fs

= 1/2 × m × v²

= 0.5 × 5 × (12)² J

= 360 J

(c) We know that the ability to do any work is called energy. That means work and energy is same.

So, the work performed is stored in the form of energy as we know according to rules of conservation of energy that- energy cannot be created nor be destroyed.

Answer 2

Answer:

(a) 49N

(b) 360J

(c) form of energy

Explanation:

A -

mass-5kg, g-9. 8m/s^2

F=mg

5×9.8

49

B-

mass-5kg v-12m/s

W-Fs

1/2mv^2

0.5×5×12^2

360J

C-

The work done performed is stored in the form of energy as we know according to rules of conservation of energy than energy cannot be created nor be created