A box is pushed a distance of 4.0 m across a floor which offers a resistance of 100 N . What is the work done by the resisting force?

Correct answer: D. -400 J Work done is given by the dot product of force and displacement vectors, W = F · d = F d (θ) . The resisting force acts in the direction opposite to the displacement, so the angle between them is θ = 180^ ^ ^ . Given F = 100 N and d = 4.0 m . W = 100 × 4.0 × (180^ ^ ^ ) W = 400 × (-1) = -400 J

Concepts Of Physics MCQ Edition [Volume 1]

Exam: Concepts Of Physics MCQ Edition [Volume 1]
Subject: Physics
Chapter: Work and Energy

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Work and Energy

A box is pushed a distance of 4.0 m across a floor which offers a...

A box is pushed a distance of

4.0 \text{ m}

across a floor which offers a resistance of

100 \text{ N}

. What is the work done by the resisting force?

Options

A $-25 \text{ J}$
B $400 \text{ J}$
C $25 \text{ J}$
D $-400 \text{ J}$

Correct answer

D. $-400 \text{ J}$

Step-by-step solution

Work done is given by the dot product of force and displacement vectors,

W = \vec{F} \cdot \vec{d} = F d \cos(\theta)

.

The resisting force acts in the direction opposite to the displacement, so the angle between them is

\theta = 180^{{}^{{}^{\circ}}}

.

Given

F = 100 \text{ N}

and

d = 4.0 \text{ m}

W = 100 \times 4.0 \times \cos(180^{{}^{{}^{\circ}}})

W = 400 \times (-1) = -400 \text{ J}

Practice Work and Energy on Quantrex Academy →

More from Work and Energy