Question

Which of the following examples involves an energy change of the system?

1) A ball rolling down a hill
2) A car driving on a flat road
3) A book sitting on a shelf
4) A person walking on a treadmill

Answer 1

Each option involves an energy change: gravitational potential to kinetic for the rolling ball, chemical to kinetic for the car, potential for the book on a shelf, and chemical to kinetic for the person on a treadmill. Energy transformations are central to these processes.

Step-by-step explanation:

All choices given involve an energy change of the system, but let's examine each:

1. A ball rolling down a hill: As the ball rolls down the hill, gravitational potential energy is converted into kinetic energy.
2. A car driving on a flat road: The chemical energy from the car's fuel is converted into kinetic energy, and there's also thermal energy due to friction.
3. A book sitting on a shelf: While it may seem static, because it's at a height, it has gravitational potential energy that could be converted to kinetic energy if it falls.
4. A person walking on a treadmill: The chemical energy in the person's body is converted into kinetic energy, and there's also electrical energy being used to power the treadmill, which can be converted into other forms such as thermal energy.

Energy transformations are a fundamental part of physics, involving the conversion from one type of energy to another. For example, riding a bicycle involves converting the chemical energy in our muscles to kinetic energy of motion, and some of that kinetic energy is converted into thermal energy due to air resistance and friction.