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?

Define 1 J of work.

Write an expression for the work done when a force is acting on an object in the direction of its displace-ment.

When do we say that work is done?

The volume of a 500 g sealed packed is 350 cm3 will the packet float or sink in water if the density of water is 1 g cm–3 ? What will be the mass of the water displaced by this packet ?

The volume of 50 g of a substance is 20 cm3. If the density of the water is 1 g cm–3 will the substance float or sink ?