Question

NUMERICALS
1. A body, when acted upon by a force of 10 kgf, gets
displaced by 0-5 m. Calculate the work done by the
force, when the displacement is (i) in the direction
of force, (ii) at an angle of 60° with the force, and
(iii) normal to the force. (g = 10 N kg-!)
Ans. (1) 50 J (ii) 25 J (iii) zero​

Answer 1

1. Explanation:

work done =FSCOSa

$10 \times 0.5 \times 1 \div 2$

work done = 25 joule

correct answer is 25 joule

Answer 2

(i) W = F × d = 100N × 0.5m = 50 J

(ii) W = F × d cosθ = 100N × 0.5m × cos60° = 25 J

(iii) Displacement is normal to the force implies that displacement is perpendicular to the force. So, W = F × d × cosθ = F×d×cos90° = 0.