Question.
Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term 'work'.
(a) Suma is swimming in a pond.
(b) A donkey is carrying a load on its back.
(c) A wind-mill is lifting water from a well.
(d) A green plant is carrying out photosynthesis.
(e) An engine is pulling a train.
(f) Food grains are getting dried in the sun.
(g) A sailboat is moving due to wind energy.
Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term 'work'.
(a) Suma is swimming in a pond.
(b) A donkey is carrying a load on its back.
(c) A wind-mill is lifting water from a well.
(d) A green plant is carrying out photosynthesis.
(e) An engine is pulling a train.
(f) Food grains are getting dried in the sun.
(g) A sailboat is moving due to wind energy.
Solution:
(a) Work is done because the displacement of swimmer takes place and a force is applied.
(b) Donkey is not doing any work in carrying the load as weight (acting vertically downward) and displacement (acting horizontal) are perpendicular to each other. But, it does work against friction between its hoofs and the ground.
(c) Work is done because the displacement of water takes place and a force is applied by the wind mill. Wind mill does a work against gravity.
(d) No work is done, because no displacement takes place.
(e) Work is done because the displacement of train takes place and a force is applied by the engine.
(f) No work is done, because displacement does not take place.
(g) Work is done because the displacement of sailboat takes place and a force is applied by the wind.
(a) Work is done because the displacement of swimmer takes place and a force is applied.
(b) Donkey is not doing any work in carrying the load as weight (acting vertically downward) and displacement (acting horizontal) are perpendicular to each other. But, it does work against friction between its hoofs and the ground.
(c) Work is done because the displacement of water takes place and a force is applied by the wind mill. Wind mill does a work against gravity.
(d) No work is done, because no displacement takes place.
(e) Work is done because the displacement of train takes place and a force is applied by the engine.
(f) No work is done, because displacement does not take place.
(g) Work is done because the displacement of sailboat takes place and a force is applied by the wind.