A mass of 4 kg originally at rest is pulled by a string along a smooth horizontal surface. The force of 15 N is maintained until the mass undergoes a displacement of 20m. at which stage the mass is allowed to keep moving at constant velocity.
How much work is done by the force ?

Explanation

To solve the problem, we need to calculate the work done by the force acting on the mass. The formula for work done (W) is given by:

\[ W = F \times d \]

where:
- \( W \) is the work done,
- \( F \) is the force applied, and
- \( d \) is the displacement.
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