Physics OCR Gateway GCSE

What are the units for gravitational field strength?

Newtons per kilogram.

Why does weight have the same units as force?

Because weight is an example of force.

On the distance-time, how is no movement represented?

Horizontal line.

What does a steep downwards gradient on a distance-time graph indicate?

Fast movement back to the starting point.

What is the formula for average speed?

Average speed = Distance moved ÷ Time taken

What is the formula for acceleration?

Acceleration = Change of the velocity ÷ Time taken

What is the symbol for start velocity?

u

On a velocity-time graph, what does a flat gradient represent?

Constant speed.

How is gentle deceleration shown on a velocity-time graph?

A gentle downwards gradient.

What does the gradient of a velocity-time graph represent?

Acceleration.

How is distance travelled represented on any velocity time graph?

The area under the graph.

Define force.

A push or a pull.

List five forces.

Weight, Magnetism, Electrostatic, Friction, Upthrust, Tension, Thrust, Reaction.

What one thing defines a scalar?

Magnitude.

What is the difference between speed and velocity?

Velocity is a vector (the direction must be specified).

What two things define a vector?

Magnitude and direction.

Is a force a scalar or a vector?

A vector.

When should forces be combined using subtraction?

When they act in opposite directions.

What is the key characteristic of friction?

It opposes motion.

What formula connects mass, acceleration and unbalanced force?

Force = Mass × Acceleration

One object has two 10,000N forces on it. A second object of the same mass has a force of 3N on it. Which will accelerate faster?

It depends on the direction of the 10,000N forces. The unbalanced (resultant) force might be 0.

What formula connects mass, gravity and weight?

Weight = Mass × Gravity

If you went to the moon, what would happen to your mass?

Nothing.

What are the two forces on a falling object in air?

Weight and friction [air resistance].

What force changes as an object falls faster?

Air resistance increases.

A force of 1000N acts upwards on a body. In what direction is it moving?

Impossible to say. It could be moving downwards and decelerating or moving upwards and accelerating.

What two elements make up stopping distance?

Thinking distance and braking distance.

What factor affects both the thinking distance and braking distance?

Speed of vehicle.

What formula links velocity, momentum and mass?

p = m × v

Why is a crumple zone in a car a safety feature?

It increases the time over which momentum is reduced.

When objects collide what is conserved?

Momentum.

What formula links change in momentum, time taken and force?

Force = change in momentum ÷ time taken

Forces always occur in pairs. True or false?

True.

When a bat hits a ball, which exerts the greater force?

The force is exactly the same.

With what size force does an object of weight 8N pull on the earth?

8N

When an object lies on the ground reaction force stops it falling. Is the reaction force a Newtonian pair with the object's weight?

No because they are of unlike type.

What is the formula for moment?

Moment = Force × Distance

Levers allow you to increase force at the expense of what?

Distance covered

What is an object's centre of gravity?

The point where all its gravity can be presumed to act.

When is an object in equilibrium?

When clockwise moments equal the anticlockwise moments.

When will the upward forces on a beam bridging a gap be equal?

When the load is in the middle.

In springs, extension is proportional to what?

Force.

An elastic band extends when a force is applied. Does it obey Hooke's law?

No, because there is no initial linear region.

When is Hooke's law obeyed?

When force is proportional to extension.

When is an object said to be elastic?

When it returns to its original shape after a force is applied.

The limit of proportionality and the limit of elasticity occur at the same point. True or false.

False. An object can extend in a non-proportional way but still return to its original length.

The Earth is the only planet to have a moon. True or false.

False.

List these in increasing order of gravitational field strength: black hole, Earth, Jupiter, Moon

Moon, Earth, Jupiter, Black hole

What causes one mass to orbit another?

Gravity.

What is the formula for orbital speed?

Orbital Speed = (2 x r) x π ÷ T

How many times does the diameter of a circle fit into the circumference?

3.14 times.

When and why do comets have tails.

When they are close enough to the Sun for the heat to melt them.

What is unusual about a comet's orbit?

It is elliptical and not in the same plane as the planets.

Place these in order of size from smallest to largest: galaxy, planet, universe, solar system.

Planet, solar system, galaxy, universe.

What is a galaxy?

A collection of billions of stars.

What is a light year?

The distance travelled by light in one year.

How far is our nearest star (other than the Sun)?

4 light years.

What is the unit for charge?

Coulomb.

State the unit of resistance.

Ohm.

Why is water around sockets a hazard?

Because it conducts electricity.

What is the function of the earth wire?

It allows a surge to occur if the device becomes live.

In what electrical safety device would you find an electromagnet?

A circuit breaker.

Name a domestic device that utilizes the heating effect of an electric wire.

Toaster.

What is the electrical energy that enters a resistor converted into?

Heat.

What formula links current, voltage and power?

P = I × V

What formula links energy, time, voltage and current?

E = VIT

What is alternating current?

A current that changes direction.

How many paths are there in a parallel circuit?

At least two.

What can make series circuits unreliable?

If one component fails all the rest receive no current.

What two factors affect the current in a circuit?

Voltage applied and number of components.

The resistance of filament lamps is constant. True or false?

False. As temperature increases resistance increases.

What is unusual about a diode?

It only lets current through in one direction.

If resistance decreases what happens to current?

It increases.

When it is cold certain resistors increase in value. What are they called?

Thermistors.

It is a bright sunny day, what happens to the current flowing through a LDR?

Goes up.

How might a flow of current be indicated other than using an ammeter?

An LED will light up.

What formula links resistance, current and voltage?

V = I × R

What is the symbol for current and why?

I, current used to be referred to as electrical intensity.

Rate of flow of charge is also known as...

Current.

What formula links charge, current and time?

Q = I × t

In a solid metallic conductor current consists of what?

Electrons.

Define a Volt.

A Joule per Coulomb.

How many electrons equal one Coulomb?

6 billion billion

Why do we use Coulombs to measure charge?

The number of electrons involved are inconveniently large.

What characterizes an insulator?

Low conductivity due to lack of free electrons.

What effect can friction have on insulating materials?

It can make them charged.

How do materials become positively charged?

A proportion of the electrons leave.

How do objects become negatively charged?

They get 'flooded' with electrons.

What happens when materials of like charge are brought together?

They repel each other.

Why do charged balloons stick to walls?

An opposite charge is induced in the wall.

What three factors make refuelling a charged aircraft dangerous?

Fuel vapour, oxygen from the air and heat from a static spark.

How do inkjet printers use electrostatic forces?

Charged plates are used to deflect the ink to the desired point on the paper.

How does electrostatic painting work?

The object to be coated and the finely sprayed paint are given opposite charges. The paint is attracted to all parts of the object evenly.

What is the function of electric charge in a photocopier?

It attracts toner to the right place.

What is the unit for frequency?

Hertz.

What category of waves does sound belong to?

Longitudinal.

Why is light classified as transverse?

Because the oscillation that causes it is at right angles to the direction of travel.

Define amplitude.

The height of the wave from the undisturbed position.

Define the time period of a wave.

The time for one wave to pass a point.

Define frequency.

Number of waves passing a point per second.