Lesson 3.2 - Work
VIDEO LESSON (15:30 min)
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Work is a physical quantity proportional to the force exerted on an object and the change in the objects position.It can be expressed as the product of the applied force and the displacement.
Its a scalar quantity measured in Joules (J).
However, this is only true for displacements in the direction of the force.
For example, if we are pushing down on a textbook sitting on a desk and the book is not moving, then no work is done.
EXAMPLE PROBLEM #1
An airport terminal employee is pushing a line of carts at a constant velocity with a horizontal force of magnitude 95 N. How much work is done in pushing he carts 16 m in the direction of the applied force? Express the answer in kilojoules (kJ).SOLUTION:
EXAMPLE PROBLEM #2
The force of friction on a sled is 120 N in the opposite direction of the sled's motion. If it takes the sled 2.4 m to stop, how much work was done by friction?SOLUTION:
Consider a force acting at an angle \( \theta \) to its displacement
EXAMPLE PROBLEM #3
A crate is being pulled by a rope with a force of \( 1.0 \times 10^2 \) N [left \( 26^o \) up]. If the crate is dragged 18 m, determine the work done.SOLUTION:
END of LESSON
Modifié le: jeudi 19 mars 2026, 10:09