Chap 6 Work, Energy, Power

Question 1

What is energy?

Answer 1

Energy is the capacity to do work. The SI unit of energy is the joule (J).

Question 2

What are the properties of kinetic energy?

Answer 2

Moving objects have kinetic energy. Kinetic energy can be used to do work.

Question 3

What is the formula for kinetic energy?

Answer 3

E=1/2mv^2

Question 4

What is gravitational potential energy defined as?

Answer 4

Gravitational potential energy (G.P.E) is the energy a body has due to its position.

Question 5

What is the formula for calculating gravitational potential energy?

Answer 5

E = mgh

Question 6

State the Principle of Conservation of Energy.

Answer 6

The Principle of Conservation of Energy states that energy cannot be created nor destroyed, but can be converted from one form to another. The total energy in an isolated system is constant.

Question 7

Why is it that a swinging pendulum eventually stops oscillating?

Answer 7

Frictional forces convert some of the total energy of a swinging pendulum to thermal energy. This thermal energy is dissipated to the surroundings and cannot be converted back into kinetic or gravitational potential energy of the pendulum. Hence the pendulum eventually comes to a stop.

Question 8

Define work done.

Answer 8

Work done is the product of the force and the distance moved by the object in the direction of the force (W = F x s). The SI unit of work is the Joule (J).

Question 9

Define power.

Answer 9

Power is defined as the rate of work done or rate of energy conversion. The SI unit of power is the watt (W) which is defined as the rate of work done or energy conversion of one joule per second.

Question 10

What is the formula for calculating power?

Answer 10

P = W/t = E/t