Answer :

When a force F acts on an object to move it in its direction through a distance S, the work is done

We know that, \( Work \ done \ = \ Force \ × \ Displacement \)

\( \Rightarrow W = F × S \)

\(\Rightarrow W = 7 × 8 \)

\(\Rightarrow \) W = 56 Nm

\(\therefore \) W = 56 J

- When do we say that work is done?
- Write an expression for the work done when a force is acting on an object in the direction of its displacement.
- Define 1 J of work.
- A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?
- What is the kinetic energy of an object?
- Write an expression for the kinetic energy of an object.
- The kinetic energy of an object of mass m, moving with a velocity of 5 m/s is 25 J. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?
- What is power?
- Define 1 watt of power.
- A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
- Define average power

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