Question

A box is pushed through 4.0 m across a floor offering 100 N resistance. How much work is done by the resisting force?
Concept of Physics - 1 , HC VERMA , Chapter " Work and Energy"

Answer 1

HEY!!

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▶Resisting force acting on the box, F=100 N

▶Displacement of the box, S = 4 m

θ=180°

▶▶Work done by the resisting force, 

W=----->.---------> =100× 4× cos180°= −400 J

Answer 2

Hello Dear.

Given data in the question :-

Resistance force (F) :- 100 N.
Displacement covered by the box (S) = 4 m .

Refer to the diagram. Shown in the attachments. 
θ = 180°

Now applying the formula :-

Work done (ω) = F. S Cos θ

ω = 100 × 4 × Cos 180°
ω = -400 J. [∵ Cos 180° = -1]

Hence the work done by the resisting force is -400 J.


Hope it Helps.