For which of the following situations is the conservation of mechanical energy most likely to be a valid assumption? a. a skateboard rolls across a sewer grate
b. a parachutist falls from a plane
c. you rub your hands together to keep warm
d. a soccer ball flies through the air

Option c is Correct!

You rub your hands together to keep warm.

Explanation:

First and foremost, mechanical energy is the sum of kinetic energy and potential energy of a system.

M.E = K.E + P.E

Where;

M.E= Mechanical energy

K.E= Kinetic energy

P.E= Potential energy

The kinetic energy is the energy possesed by a moving body, while the Potential energy is possesed by a stationary body.

When you rub your hand together to produce heat that keeps you warm, there is conservation of energy.

According to the first law of thermodynamics also known as the energy conservation law: it states that energy can neither be created nor destroyed, but can be transformed from one form to another.

The rubbing of the hand creates a motion(Kinetic energy) between the palms, this motion is opposed by a force called friction. thus the generation of heat accounts for the transfer of energy from Kinetic to Heat energy, therefore Mechanical energy is conserved according to the law of thermodynamics

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.