Chapter 8: Motion and Energy

Question 1

Define speed

Answer 1

How fast something moves.
Speed= distance/time

Question 2

Explain the difference between average speed and instantaneous speed.

Answer 2

Average speed is defined as the total distance travelled divided by the total time elapsed while instantaneous speed is the speed recorded at a specific time or instant.

Question 3

Identify ways of measuring speed

Answer 3

Speedometer, speed camera or ticker timer.

Question 4

Interpret displacement/time and velocity/time graphs.

Answer 4

Learn this!

Question 5

Identify that the acceleration due to gravity at the Earth’s surface is…

Answer 5

9.8m/s/s

Question 6

Explain Newton’s first law and identify everyday examples.

Answer 6

(Law of Inertia) An object stays at rest or keeps going in a straight line at the same speed unless it is acted on by an unbalanced force. E.g A ball is thrown and falls down towards earth due to gravity or a stationary object will not move unless acted upon by a force.

Question 7

Explain Newton’s second law and identify everyday examples.

Answer 7

(Law of acceleration) Force = mass x acceleration or F=ma E.g When riding a bike, the bike is the mass and your legs are the force pushing the bike along the ground

Question 8

Explain Newton’s third law and identify everyday examples.

Answer 8

(Law of force pairs OR Law of action/reaction) For every action there is an equal and opposite reaction. E.g A book on a table has a downward force of its weight, while the table pushes upwards on the book.

Question 9

Recall the law of conservation of energy. Use this law to identify energy transformations.

Answer 9

The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another.
E.g Fire: Heat → light
Electric lamp (electrical energy → heat and light)