Editor Staff asked 1 year ago
A person of mass 50 kg carrying a load of 20 kg walks up a staircase. The width and height of each step are 0.25 m and 0.2 m respectively. What is the work done by the man in walking 20 steps?(Assume g = 10m/s^2)
(a) 800 J
(b) 1600 J
(c) 2000 J
(d) 2800 J
I got this question in class test.
I would like to ask this question from Work Done by a Variable Force topic in chapter Work, Energy and Power of Physics – Class 11
Select the correct answer from above options
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Editor Staff answered 1 year ago
Correct choice is (d) 2800 J
Best explanation: Total mass (m) = 50 + 20 = 70 kg
Vertical displacement = 0.2 x 20 = 4m
Horizontal displacement = 0.25 x 20 = 5m
Displacement = (5i + 4j) m
Force = m x acceleration
= 70 x (0i + 10j)
= (700j) N
Work = Force .Displacement
= (0i + 700j) . (5i + 4j)
= 2800 J.
