Physics

Question 1

What is speed?

Answer 1

Speed can be defined as the rate at which someone or something moves or can move.

Question 2

What are the units for speed?

Answer 2

Speed must always be expressed as a unit of distance divided by a unit of time. The scientific (SI) unit for speed is m/s.

Question 3

How do we calculate average speed?

Answer 3

Average speed can be calculated by dividing the total distance travelled by the total time taken.

Question 4

What are the DTS Triangle formulas?

Answer 4

v = speed | d = distance| t = time

v = d / t
d = v x t
t = d / v

Question 5

What is Distance?

Answer 5

The physical length of the actual path travelled by someone or something is known as distance. It is a scalar quantity, and its value can not be 0.

Question 6

What is Displacement?

Answer 6

Displacement is the straight-line distance between the start and finish points, which is also the shortest possible distance. It is a vector quantity, and its value can be 0.

Question 7

What is the difference between Speed and Velocity?

Answer 7

Speed is the rate at which distance is covered; it is a scalar quantity requiring only magnitude (e.g., km/h).
Velocity is the rate of change in position; it is a vector quantity requiring both magnitude and direction.
Speed measures the total distance travelled, while velocity measures displacement over time.

Question 8

Speed vs Velocity Definitions

Answer 8

Speed is the scalar quantity that signifies only the magnitude of the rate of change of an object’s movement.
Example: 25m/s

Velocity is the vector quantity that signifies the magnitude of the rate of change in position and the direction of an object’s movement.
Example: 25 m/s north.

Question 9

How do we calculate average velocity?

Answer 9

Average velocity can be calculated by dividing the total displacement travelled by the total time taken.

Question 10

Average vs Instantaneous Speed

Answer 10

The average speed looks at the entire journey: total distance and time.
The instantaneous speed is the car’s speed at any given point along the journey.

Question 11

What types of devices can calculate speed?

Answer 11

Sonic Motion Sensors
Speedometers
Radar Guns – send out radio waves
Laser guns – send out pulses of light
Digitectors – two cables laid across the road at a fixed distance
Global Positioning System (GPS)
Personal Sports Trackers

Question 12

What is a ticker timer?

Answer 12

A ticker timer can be used to record motion in the science lab.

A vibrating arm hits a disk of carbon paper 50 times each second, leaving black dots that are a fiftieth of a second apart.

We can measure the average speed between each pair of dots by dividing the distance by the time interval.

Question 13

How do we analyse ticker timers?

Answer 13

The more distance between each dot, the faster the tape traveled.

To make calculations easier, every fifth dot can be used.

Five dots represent five-fiftieths of a second (5/50) – which is 0.1s

Question 14

What is acceleration?

Answer 14

Acceleration is a measure of the rate at which velocity changes.

The SI unit for acceleration is m/s2

Question 15

How do we calculate average acceleration?

Answer 15

The average acceleration can be calculated by dividing the change in velocity by the time taken for the change.

Question 16

What does a positive/negative acceleration mean?

Answer 16

A positive value for acceleration shows speeding up.

A negative value for acceleration shows slowing down.

Slowing down is also called deceleration.

Question 17

What is the standard velocity of gravity?

Answer 17

Near the earth’s surface, the acceleration due to gravity is 9.8 m/s^2.

Question 18

How do acceleration values work?

Answer 18

For example – a ball is dropped off a cliff at a starting velocity of 0 m/s.

After 1 second, its velocity has increased to 9.8 m/s

After 2 seconds, its velocity is 19.6 m/s (9.8 + 9.8)
etc.

The velocity continues to increase at 9.8 m/s/s.

Question 19

What is a distance-time graph?

Answer 19

A distance-time graph compares the distance and time on each axis.
x-axis = time
y-axis = distance

Therefore, the slope (gradient) of a distance-time graph represents velocity.

Question 20

What do the slopes on a distance-time graph mean?

Answer 20

The slope can be positive, negative, or zero.

A constant slope means a constant velocity.

A curve shows a changing slope, which means a changing velocity.

As the slope of the line becomes steeper, the object’s velocity becomes greater.

Question 21

What is a velocity-time graph?

Answer 21

A velocity-time graph compares the velocity and time on each axis.
x-axis = time
y-axis = velocity

Therefore, the slope (gradient) of a distance-time graph represents acceleration.

Question 22

What do the slopes on a velocity-time graph mean?

Answer 22

Acceleration = change in velocity over time.

A horizontal line = constant velocity.

A straight sloped line = constant acceleration.

Positive slope = acceleration.

Negative slope = deceleration.

Question 23

What is velocity-time graph displacement?

Answer 23

The area under the curve to the Y-axis represents the object’s displacement. Simple geometry formulas can find this area.

Question 24

What is Newton’s First Law of Motion?

Answer 24

An object will not change its motion unless an external force acts upon it. This is also known as the Law of Inertia.

Question 25

What are the forces acting upon a bus?

Answer 25

The forces on the bus are equal.
The upward push of the road (up) = weight (down) - gravity
The thrust (forward) = the resistant forces (backward) - air resistance and friction)

This means the bus is travelling at a constant speed.

Question 26

What is Inertia?

Answer 26

Inertia is the property of objects that makes them resist changes in their motion.

The greater the mass of an object, the more inertia it has.

Question 27

What is momentum?

Answer 27

Momentum is a measurement of mass in motion. Any object that is moving has momentum. In physics, the momentum of an object is equal to the mass times the velocity.

momentum = mass x velocity
p = mv

Question 28

What is gravity?

Answer 28

Gravity is the force of attraction between objects with mass, pulling them towards each other.

Question 29

What affects gravity?

Answer 29

The size of the force of gravity between two objects depends on their mass and the distance between them.

We usually only notice gravity when at least one of the two objects has a very large mass, like the Earth.

Question 30

Which objects exert a greater force to influence the gravitational pull?

Answer 30

The Earth, having greater mass, exerts a stronger force on the skydiver, though the forces between them are equal and opposite.

The Earth’s mass causes a much larger pull on the skydiver than the skydiver does on the Earth.

Question 31

What is Weight?

Answer 31

The weight of an object is a measure of the force of gravity on the object.
SI Units – Newtons

Weight = mass x gravity

On Earth, g = acceleration due to gravity = 9.8 m/s^2.

Question 32

What is mass?

Answer 32

The mass of an object is a measure of the amount of matter in an object.

It is a constant.

SI Units – kilograms.

Question 33

Is Gravity Independent of Mass?

Answer 33

Yes. Until Galileo, “common sense” told people that heavier objects fall faster.

Ignoring air resistance - objects of different masses fall with the same acceleration due to gravity.

Question 34

What is Newton’s Second Law of Motion?

Answer 34

An object’s mass affects how it moves when acted upon by one or more forces.

The force on an object is equal to its mass times its acceleration. The equation represents this: f = m x a.

Question 35

What is Newton’s Third Law of Motion?

Answer 35

When two objects interact, they apply forces of equal magnitude and opposite direction to each other. This is also known as the law of action and reaction.

Question 36

What is another way to put Newton’s Third Law of Motion?

Answer 36

When an object applies a force to a second object, the second object applies an equal and opposite force to the first object. Forces always occur in pairs.

Question 37

What is an example of Newton’s Third Law of Motion?

Answer 37

As the gases from the gunpowder explosion expand, the gun pushes the bullet forward, and the bullet pushes the gun backwards. The
Action Force: The gun pushes the bullet forward.
Reaction Force: The bullet pushes the gun backward.

More Acceleration: The bullet has more acceleration because it has less mass than the gun.
Less Acceleration: The gun because it has more mass.

Question 38

What is “work” in physics?

Answer 38

Whenever you apply a force to an object, the object moves in the direction of the force. Work is done to the object.
SI Units for Work = Joules (J)

Question 39

What does “work done” mean?

Answer 39

For work to be done, the object must move toward the force.

Work done = force x distance travelled in the direction of the force.

Question 40

What is an example of work being done?

Answer 40

The weightlifter does work to lift the weight.

He applies an upward force, and the weights move up.

However, if he holds the weights still, no work is done on them as no distance is travelled.

Question 41

What is the correlation between work and energy?

Answer 41

Energy can be transferred to an object by doing work on it.

Working on an object can transfer energy from one form to another.

Remember - The Law of Conservation of Energy.
Energy cannot be created or destroyed; it can only change form.

Question 42

What is an example of work and energy on an object?

Answer 42

If you lift a 5kg bowling ball with a force of 49 newtons through a height of 40 cm. How much work or change of energy has been done on the bowling ball?
Work = Force x Distance
= 49 N x 0.4 m
= 19.6 J
By doing work on the bowling ball we have transferred 19.6 joules of energy to it.
The additional energy is stored as gravitation potential energy.
It has the potential to be converted to other forms of energy or be transferred to other objects.
If you drop the ball the force of gravity can work on the ball increasing its kinetic energy.
The kinetic energy can be transferred to heat and sound as it hits the ground.

Question 43

What are the Types of Energy?

Answer 43

Nuclear Energy
Kinetic Energy
Electrical Energy
Light Energy
Thermal Energy
Sound Energy
Elastic Potential Energy
Chemical Energy
Gravitational Potential Energy

Question 44

What is Kinetic Energy?

Answer 44

Energy of Movement.

Question 45

What is Potential Energy?

Answer 45

Stored Energy.

GPE = mgh

m = mass | g = acceleration due to graivty| h = height

Question 46

What are the types of Potential Energy?

Answer 46

Gravitational PE – stored energy due to its height from which it can fall.

Chemical PE– stored energy in foods and fuels. Chemical reactions occur, converting the stored energy.

Elastic PE– stored energy in stretched or compressed objects.

Nuclear PE– stored energy in the nucleus of an atom.

Electrical PE– is present in objects where the positively and negatively charged particles are separated.

Question 47

What is Total Mechanical Energy (TME)?

Answer 47

TME stands for Total Mechanical Energy. It is the sum of an object’s kinetic energy (KE) and gravitational potential energy (GPE). The value of this will always stay as a whole.