13. Exercises XIII

1. Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?

 

When we push a huge rock unsuccessfully, there’s transferno transfer of muscular energy to the stationary rock. Also, there’s no loss of energyloss of energy since Muscular energy → Heat energyMuscular energy → Kinetic energyMuscular energy → Kinetic energy + Heat energy.

 

2. What is the work done by the force of gravity on a satellite moving round the earth? Justify your answer.

 

If the direction of force is inlineperpendicularparallel to displacement, then the work done is zerohignlow.

 

When a satellite moves around the Earth, then the force of gravity on the satellite is perpendicularinlineparallel to its displacement. Therefore, the work done on the satellite by the Earth is hignzerolow.