4.4.7 Conservation of Energy in General

Question 1

Conservation of Energy in General

Answer 1

• The term in the equation includes many different forms of potential energy including gravitational, spring,and chemical potential energy.
• There are four fundamental forces of nature: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force.
• is the most general statement of conservation of energy.
• When there is friction, kinetic energy is converted into thermal energy in the molecules of the surfaces in contact.

Question 2

In the science fiction story “The Matrix”, humans are used to generate energy for machines. Which of the following explains how this would be possible in the real world?

Answer 2

Energy can be converted from one form to another.

Question 3

Electric motors work from the conversion electrical energy into mechanical energy by using electric forces to turn a rotor. Electric generators work by converting mechanical energy into electric energy by spinning a similar rotor. An electric motor is connected to an electric generator by a shaft going through both rotors, and started spinning by an external force. The electricity produced by the generator is then transferred to the motor in the hopes of getting each machine to power the other indefinitely. Which of the following states why this will not work?

Answer 3

Energy would be lost by nonconservative forces.

Question 4

Glow sticks can provide light for several hours without the aid of any external energy source. Which of the following is the reason why glow sticks do not violate the law of conservation of energy?

Answer 4

They emit light by using energy that was stored as potential energy.

Question 5

True or false?

The total energy contained in a closed system is always constant.

Answer 5

true

Question 6

In the formula delta K + delta U = 0, potential energy _________

Answer 6

must come from a conservative force

Question 7

Which of the following is not a typical method of storing mechanical potential energy?

Answer 7

As heat

Question 8

Which of the following is not a fundamental force of nature?

Answer 8

Friction

Question 9

Delta K + Delta U = Wother, Wother is

Answer 9

work done by any external force

Question 10

In a diesel engine, hot exhaust gases ignite the incoming fuel fumes to keep the engine going, without the assistance of any electrical systems. Which of the following states why this does not violate the law of conservation of energy?

Answer 10

The fuel continues to provide chemical energy.