# 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)

Category: QuestionsA 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)
Editor">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">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.

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