Question

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Answer 1

Answer:

Ans. F=7N

s = 8 m

W = F × s

= 7 N × 8 m

W = 56J

∴ Work done is 56 J.

NCERT TEXTBOOK PAGE 149

Q1. When do we say that work is done?

Ans. Work is said to be done when force applied on an object shows the displacement in that object.

W = F x s.

Q2. Write an expression for the work done when a force is acting on an object in the direction of its displacement.

Ans. Work done = W

Force = F

Displacement = s

Work done is equal to the product of the force and displacement.

W = F × s

Q3. Define 1 J of work.

Ans. 1 Joule of work is said to be done when force of 1 Newton acts on a by and shows displacement of 1 metre.

Q4. A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?

Ans. Force = 140 N

s = 15m

W = ?

W = F × s

= 140 N x 15 m

= 2100 Nm

W = 2100 J

∴ Work done in ploughing the length of the field is 2100 J.