Question

a) How are work, force and distance related.
b) Find the work done by a pulley when it lifts a block which is $5M$ off the ground with a $10N$ force.

Answer 1

Hint: Recall the definitions of work, force and distance. They are related by a single equation. Work is done when there is some displacement by some applied force. To solve the (b) part of the question, we can simply apply the definition of work done and calculate the value.

Complete step by step solution:
a) Let us first define each term and then relate them.
Force: A force maybe a push or pull acting upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force acting upon each of the objects and the magnitude of this force may be the same or different. When the interaction ceases, the two objects no longer experience the force and may move with constant velocity or may be at rest. Force is denoted by the symbol $\overrightarrow F $ .
Distance: Distance is the total path covered by a moving body.
Work: Work is said to be done when a force acting on a body is able to displace the body by some units. Work is concerned with displacement and not with distance. Displacement is the minimum distance between the initial and final position. Work is denoted by $W$ .

b) Work done is the dot product of force and displacement. Since no angle is mentioned in the question, we will consider the angle between force and displacement to be zero.
$ \Rightarrow W = 50J$
Where $\overrightarrow s $ is displacement.
$ \Rightarrow W = Fs\cos \theta $
Since angle is zero, therefore $\cos \theta = 1$
$ \Rightarrow W = 10 \times 5$
$ \therefore W = 50J$

Therefore, $50J$ of work is done by the pulley.

Note: Remember that force is a vector quantity, it has magnitude as well as direction. Work done is calculated by multiplying the magnitude of force and displacement when angle between force and displacement is zero. When the force and displacement are perpendicular to each other, work done is zero.