How Does Energy Transform into Force During Physical Interactions?

[Peter G.]

I understand that, when we do work, we are exerting a force over a distance and to exert a force, we need energy. Let's see:

For example, to push a car: Energy stored in our muscles is used to exert a force to push the car, giving it Kinetic Energy. Energy stored in our muscles was transformed into Kinetic Energy.

Now, when a car hits a wall, it exerts a force on the wall which depends on the amount of energy it has. I don't understand how the energy of the car is transformed into a force.

Basically, what confuses me is the relationship between Force, Energy and Work.

Can anyone help me with this?

 

[Andrew Mason]

I understand that, when we do work, we are exerting a force over a distance and to exert a force, we need energy. Let's see:

For example, to push a car: Energy stored in our muscles is used to exert a force to push the car, giving it Kinetic Energy. Energy stored in our muscles was transformed into Kinetic Energy.

Now, when a car hits a wall, it exerts a force on the wall which depends on the amount of energy it has. I don't understand how the energy of the car is transformed into a force.

Basically, what confuses me is the relationship between Force, Energy and Work.

Can anyone help me with this?

Energy is not an intuitive concept. It was not developed until the 19th century, over a century after Newton developed his laws of motion. It is a mathematical concept. It is useful because it is a quantity that is conserved in some form during interactions, but not necessarily in the form of motion.

Think in terms of momentum. Momentum is always conserved in the same form: motion. Force is the rate of change of momentum with time. Newton thought of this as the quantity of motion. As the car hits the wall its momentum changes. The change of momentum of the car occurs rather rapidly so the force is high.

Force is also the rate of change of energy with distance. Because the wall does not "give", the rate of change with energy with distance is also high - the car loses its energy over a very short distance, so the force will be high.

AM