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Question
A girl weighing 400 N climbs a vertical ladder. If the value of g be 10 m s−2, the work by her after climbing 2 m will be :
Options
200 J
800 J
8000 J
2000 J
Solution
Weight of the girl (W) = 400 N
Vertical height (h) = 2 m
Acceleration due to gravity (g) = 10 m/s2
We can calculate the work done against gravity in moving a body of mass (m) by a height (h) as,
Work done in lifting a body = (Weight of body) (Vertical distance)
So,
W = (m)(g)(h)
So,
Work done in lifting a body
= (400)(2) J
= 800 J
Therefore, the answer is:
(b) 800 J.
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