Question 5
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road.
The work done against the gravitational force will be (g = 10 ms)
a) 6 x 10°)
(b) 6
(c) 0.6 ]
(d) zero
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✪ AnsWer :- ✪
- Mass of bag = 3 kg
- Acceleration due to gravity (g) = 10 m/s²
- Displacement (s) = 200 m
The force is acting here is Force of gravity which is always directed towards down and Displacement of the girl is in the horizontal direction. The angle made by force of gravity and displacement is 90°.
✪ Work done by the girl against gravitational force is : ✪
→ W = Fs cos(θ)
→ W = mgs cos(θ)
→ W = 3 × 10 × 200 × cos (90°)
→ W = 3 × 10 × 200 × cos (90°)
→ W = 6000 × cos (90°)
- cos (90°) = 0
→ W = 6000 × 0
→ W = 0 J
- Hence,the work done by against the gravitational force will be (D) zero.
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