Physics Revision - Science

Question 1

What is displacement?

Answer 1

How far you are from the starting point - including direction.

Question 2

What is distance?

Answer 2

How far you have travelled.

Question 3

A person walks 4km from their home, then 4km back and then 2 km south.
What is the displacement and distance?

Answer 3

The displacement is 2 km south from their home.
The distance is 4 + 4 + 2 = 10 km

Question 4

What is the equation for average speed?
And how do you find the other variables?
(Hint - average speed triangle)

Answer 4

Average speed (Sav) = distance (d) / time (t)
Time (t) = distance (d) / average speed (Sav)
Distance (d) = average speed (Sav) x time (t)

Question 5

What is a vector quantity?

Answer 5

A thing that measures both magnitude and direction.

Question 6

What is a scalar quantity?

Answer 6

A thing that measures only magnitude.

Question 7

Is speed a scalar or vector quantity?

Answer 7

Scalar

Question 8

What is velocity?

Answer 8

A vector quantity that measures the speed in a particular direction.

Question 9

What is the average velocity equation?
And how do you find the other variables?
(Hint - average velocity triangle)

Answer 9

Average velocity (Vav) = displacement (d) / time (t)
Time (t) = displacement (d) / average velocity (Vav)
Displacement (d) = average velocity (Vav) x time (t)

Question 10

How do you find the displacement in a velocity time graph?

Answer 10

Calculate the area under the graph and calculate the total area of all the shapes under the graph.
(Distance is all added together even if there are negative numbers)

Question 11

What is acceleration?

Answer 11

The rate at which the velocity or speed of an object changes.

Question 12

What is the acceleration value of 10 m/s2 or 9.8 m/s2 called?

Answer 12

Acceleration due to gravity.

Question 13

How do you calculate acceleration?
And how do you calculate other variables?
(Hint - acceleration triangle)

Answer 13

Acceleration (Aav) = change in velocity / change in time or final velocity - starting velocity / final time - starting time.
Change is velocity = acceleration x change is time
Change in time = change in velocity / acceleration

Question 14

What is Newton’s first law called?

Answer 14

The law of Inertia

Question 15

What does Newton’s first law state and mean?

Answer 15

States that ‘An object remains at rest or in a constant motion in a straight line unless acted on by a net unbalanced force.’
This means that an object with two forces equal in magnitude and opposite in direction (push and pull) has balanced forces and the motion remains the same. To cause movement or motion another force must be added to cause the forces to become unbalanced.

Question 16

What is Inertia?

Answer 16

Inertia is the tendency of an object to resist change in motion and keep in the existing state of motion.

Question 17

What is an example of Newton’s First Law?

Answer 17

When someone is sitting on a chair, the chair is being pulled down due to gravity (its weight force). It doesn’t move because there is another force, equal in magnitude to the weight force but acting in the opposite direction, pushing the chair up from the surface.

An example of Inertia is when a passenger of a vehicle is not wearing their seatbelt and the car comes to a stop, the passenger will continue to move forward due to inertia.

Question 18

What does Newton’s second law state and mean?

Answer 18

States that ‘The acceleration of an object is directly related to the magnitude and direction of the net force acting on the object and inversely related to the mass of an object.’
Net force (Fnet) = mass (m) x acceleration (a)
Mass (m) = Net force (Fnet) / acceleration (a)
Acceleration (a) = Net force (Fnet) / mass (m)

Question 19

What is net force?

Answer 19

The vector sum of all the forces acting on an object.
If the forces are acting in opposite directions, it is force 1 - force 2.
If the forces are acting in the same direction it is force 1 + force 2.

Question 20

What is weight?

Answer 20

Weight is the force from gratify acting on an object and is measured in Newtons (N).
Weight (w) = mass (m) x gravitational acceleration (g)
Mass = weight (w) / gravitational acceleration (g)
Gravitational acceleration (g) = weight (w) / mass (m)

Question 21

What does Newton’s third law state and mean?

Answer 21

States that ‘For every action, there is an equal and opposite reaction.’
The action force is the initial force of an object while the reaction force is the force acting in the opposite direction to the initial force. Action-reaction pairs always act on different objects and can not cancel each other out.

Question 22

What is an example of Newton’s Third law?

Answer 22

When you lean against a wall you exert force onto the wall (the action force) so the wall exerts a force onto you (the reaction force).

Question 23

What is momentum?

Answer 23

It is mass in motion and is the product of the mass and velocity of an object.

Question 24

What is the law of conservation of momentum?

Answer 24

The law of conservation of momentum states that in an isolated system (the set of objects that interact in a collision), the total momentum does not change during a collision, however momentum is passed along from one object to another.
This means the initial momentum and final momentum are equal.

Question 25

How is momentum calculated?
And how do you calculate the other variables?

Answer 25

Momentum (P) = mass (m) x velocity (v)
Mass (m) = momentum (p) / velocity (v)
Velocity (v) = momentum (p) / mass (m)

Question 26

What are the units for distance and displacement, speed, velocity, acceleration, mass, momentum and force?

Answer 26

Distance = mm, cm, m, km
Displacement = mm, cm, m, km and North, South, East, West.
Speed = m/s
Velocity = m/s and N, S, E, W
Acceleration = m/s2
Mass = kg, g
Momentum = kg m/s
Force = N (newtons)