Question

How much work does a person do in pushing a box with a force of 20 N over a distance of 80 m in the direction of the force?
(A) 1.6 J
(B) 16 J
(C) 160 J
(D) 1600 J
(E) 16000 J

Answer 1

Hint: Use the concept that the work done on the object by the constant force can be determined by multiplication of the distance moved by the object due to the effect of force and force in the direction of the displacement.

Complete step by step answer:
It is given that the magnitude of the applied force over the box is 20 N and due the effect of this force the displacement of the box is 8.0 m in the direction of the force.
Let the work done by the person is $w$.
The expression used for the calculation of work done by the person on any object is
$w = fd$
Here, $f$ is the force applied by the person and $d$ is the displacement of the box.
Substitute the values of applied force and displacement of the box in the above equation.
Therefore we get,
$\begin{array}{l} w = fd\\\ w = 20\;{\rm{N}} \times 8\;{\rm{m}}\\\ w = {\rm{160}}\;{\rm{N}} \cdot {\rm{m}}\\\ w = 160\;{\rm{J}} \end{array}$
Hence, option (C) is correct, that is $160\;{\rm{J}}$.

Note: Remember that the mechanical work can be obtained with the help of applied force, and the calculation of this work depends on the displacement of the object. If the value of the object's displacement is zero, then the work done on the object also must be zero.