JIPMER2017PhysicsWork, Power and Energy
Two 20 g flatworms climb over a very thin wall, 10 cm high. One of the worm is 20 cm long, the other is wider and only 10 cm long. Which of the following statement is correct regarding them?
Options
- A20 cm worm has done more work against gravity
- B10 cm worm has done more work against gravity
- CBoth worms have done equal work against gravity
- DRatio of work done by both the worms is 4: 5
Correct answer
B. 10 cm worm has done more work against gravity
Step-by-step solution
The work done against gravity can be calculated from the increases in height of the centre of mass. The centre of mass of a worm folded in two is located at the middle of either half, i.e. at a point one-quarter of the worm's total length from one end, as given in the figure below: Thus, the centre of mass of the narrow flat worm travels 5 cm up the wall; while that of the broad one moves 7.5 cm . Hence, work done by 10 cm worm is more against gravity. Also,the ratio of the work done is 2: 3 .