Question

A rocket is at rest on the launch pad. When the rocket is launched, its kinetic energy increases.

Consider all of the forces acting on the rocket during the launch, and decide whether the following statement is true or false:

The amount by which the kinetic energy of the rocket increases during the launch is equal to the work done by the force generated by the rocket's engine.

Answer 1

First statement: True

Second statement: FALSE

Step-by-step explanation:

As we know that the kinetic energy is the energy of a body possessed by the virtue of its motion.

As the rocket is at rest on the launchpad its kinetic energy is zero, but as it gets launched from its launchpad its kinetic energy increases.

The force of air resistance acts downward on the rocket while the thrust acts downward on the launchpad pushing the rocket upwards.

The total work some by the engine is not converted into the kinetic energy of the rocket because a lot of heat is produced during the fuel combustion of which not all the energy is utilized, some energy is used in overcoming the friction between the moving parts and other basic necessities.

Answer 2

False.

Step-by-step explanation:

The forces acting on the rocket would be the engine pushing it forward, but it would also be the force of gravity and air friction acting in the reverse direction of the force of the engine. And so some energy in the form of heat, vibration, etc. would be lost to these forces, and the maximum amount of work would not be converted into kinetic energy.

So it's wrong with the statement. The work done by the engine-generated power would be higher than the Kinetic energy, as some of the energy is lost to non-conservative forces (gravity, air resistance, etc.).