GCSE Physics (Paper 2)

What is a vector quantity?

A quantity with magnitude (size) and direction

What examples are there of vector quantities?

Any force, velocity, displacement, acceleration, momentum

What is a scalar quantity?

A quantity with magnitude (size) only

What examples are there of scalar quantities?

Speed, distance, mass, temperature, time

How are vectors represented in a diagram?

With an arrow

How is the magnitude and direction of a force represented in a vector diagram?

The length represents the size of the quantity and the arrowhead the direction

What is a force?

A push or pull acting on an object

What is a contact force?

A force exerted when the objects are physically touching

What examples are there of contact forces?

Friction, air resistance, tension, normal contact force

What is a non-contact force?

A force exerted on objects that are physically separated

What examples are there of non-contact forces?

Magnetic force, gravitational force, electrostatic force

What happens when two objects interact?

A force is produced on both objects

What is an interaction pair?

Forces that are equal in size and opposite in direction

Which of Newton's Laws of motion is defined by an interaction pair?

Third law

What is a gravitational force?

An attraction force that acts between masses

When do we notice a gravitational force?

When one of the masses is very, very big, like a planet or star

What is mass?

The amount of matter an object is made of

What is the standard unit of mass and its unit symbol?

Kilograms, kg

What is weight?

A force acting on an object due to gravity

What is the unit for weight and all other forces and the unit symbol?

Newton, N

What does the weight of an object depend on?

The strength of the gravitational field and the mass of an object

What is meant by the term "centre of mass"?

An assumption that identifies a single point on object where the whole mass is concentrated

What is the relationship between weight and mass, when gravity is constant?

They are directly proportional

How is weight measured, practically?

Using a calibrated spring balance (a newtonmeter)

What is a free body diagram?

A diagram that shows all of the forces acting on an object

How are forces represented on a free body diagram

With an arrow, the length represents the size of the force and the arrowhead the direction of the force. (arrows always point away from the object)

What is a resultant force?

The overall force acting on an object

What happens when a resultant force moves an object?

Energy is transferred between energy stores and work is done

What does "resolving" a force mean?

Splitting a force into its horizontal and vertical components

What is true of the forces on an object that is in equilibrium?

Forces are balanced or there is an overall resultant force of zero

What three deformations can happen to an elastic object when forces are applied?

Stretching, compressing and bending

What is an elastic deformation?

The object will return to its original size and shape when forces are removed

What is an inelastic deformation?

One in which the object will not return to its original size and shape when forces are removed

Give two examples of elastic objects

A spring and a sponge

What type of energy is stored in a stretched spring?

Elastic potential energy

How do you calculate the extension of a spring?

Length of spring with force applied - original length of spring

How is the extension of a spring related to the force added?

Extension is directly proportional to the force added (up to a limit)

What does the spring constant depend on?

The stiffness of the spring

If you increase the stiffness of a spring what happens to the size of the spring constant?

It increases

How can you calculate the spring constant from a force-extension graph?

Calculate the gradient of the linear part (straight part) of the graph

On a force-extension graph, what does a steeper line represent?

A stiffer spring with a larger spring constant

When measuring a spring with a ruler, why must the ruler be parallel?

To increase the accuracy of the reading

When reading a vertical scale, what is meant by a parallax error?

The reading changes depending on where you are looking from

How do you prevent a parallax error from occurring?

Always read the measurement at eye level

Give two reasons to do a pilot or preliminary experiment

To find an appropriate interval size for the independent variable i.e one that gives measurable results. To check that the method works.

What type of quantity is distance?

Scalar

What type of quantity is displacement?

Vector

How is displacement different to distance?

Displacement is a vector quantity, measuring the distance and direction in a straight line from the starting point

What is the difference between speed and velocity?

Speed is a scalar quantity and velocity is a vector quantity

What two quantities do you need to measure to calculate speed?

Distance travelled and time taken

What symbol is used to represent distance?

s

What is the standard unit and unit symbol of distance?

Metres, m

What symbol is used to represent speed (velocity) and

v

What is the standard unit and unit symbol of velocity?

Metres per second, m/s

Why are most speeds said to be average speeds?

Objects rarely travel at a constant speed, they speed up and slow down.

What is the typical average speed for a person walking?

1.5 m/s

What is the typical average speed for a person running?

3.0 m/s

What is the typical average speed for a person cycling?

6 m/s

What is the typical average speed for a car?

25 m/s

What is the typical average speed for a train?

55 m/s

What is the typical average speed for a plane?

250 m/s

What is the speed of sound in air?

330 m/s

What is meant by acceleration?

Change in velocity in a certain amount of time

What happens to an objects velocity when it is travelling in a circle?

It is constantly changing

Why is travelling at a constant speed in a circle considered to be an example of constant acceleration?

Velocity is constantly changing due to the direction constantly changing

What is the standard unit and unit symbol for acceleration?

Metres per second squared, m/s2

What is meant by uniform acceleration?

constant acceleration

What is the acceleration due to gravity near the Earth's surface?

9.8 m/s2

On a distance-tine graph what does a straight line with a gradient represent?

Constant speed

What does a horizontal line on a distance-time graph represent?

The object is stationary

What does a curve represent on a distance-time graph?

Acceleration or deceleration

How can you calculate the acceleration from a curve on a distance-time graph?

Draw a tangent to the curve and calculate the gradient

On a velocity-time graph what does a straight line with a gradient represent?

Constant acceleration

What does a horizontal line on a velocity-time graph show?

Constant speed

What is different about the lines on a velocity-time graph which show acceleration and deceleration?

Acceleration is a line moving up the graph, deceleration is a line moving down the graph

How do you use a velocity-time graph to calculate the distance travelled by an object?

Calculate the area under the graph

Which force always acts in the opposite direction to motion?

Friction

What other name is given to the force of friction due to objects moving through a fluid?

Drag

When an object speeds up, what happens to the friction/drag force?

Increases

How can you reduce the effect of drag on a moving object?

Make it more streamlined

What force causes a falling object to accelerate?

Gravity

What force acts against gravity?

Drag/friction

What is meant by the terminal velocity of a falling object?

Maximum constant velocity

When does a falling object reach terminal velocity?

When the weight of the object is equal to the force of drag so the resultant force is zero

Why do objects fall at different speeds on earth when they have the same acceleration force due to gravity?

Friction forces due to air resistance depends on the shape and surface area of the object

State Newton's First Law

A resultant force is needed to make an object start moving, speed up, slow down or change direction.

What are the two possible conditions of an object with a resultant force of zero?

It must be stationary or moving at a constant velocity

State Newton's Second Law

The acceleration of an object is directly proportional to the force applied

What is inertia?

The tendency of an object to continue in their state of rest or of uniform motion

What is inertial mass and how is it calculated?

Measure of how difficult it is to change the velocity of an object, m= F ¸a

State Newton's Third Law

Whenever two objects interact, the forces they exert on each other are equal and opposite

What symbol represent 'approximately'

̴

What is meant by the "Stopping Distance" of a car?

The total distance travelled by a car in an emergency

State the two components of the total stopping distance of a car

Thinking distance and braking distance

What is the thinking distance?

The distance a car travels between seeing a hazard and the brakes being applied (the drivers reaction time)

What does typical human reaction time range between?

0.2s to 0.9s

What two key factors affect the thinking distance of a car?

The speed the car is travelling and the reaction time of the driver

What factors will increase the time it takes for a driver to react?

Alcohol, distractions, tiredness

What factors will increase the braking distance of a car?

Worn tyres, poor brakes, slippery roads (wet or icy)

What happens to the overall stopping distance as speed increases?

It increases