year 10 mocks combined set

What is a fluid?

A substance that can flow, which includes liquids and gases.

What is the unit of pressure that is equal to one newton per square metre?

Pascal (Pa).

Why does the pressure in a liquid increase with depth?

The pressure at any point in a liquid is due to the weight of the liquid above that point.

Why does the pressure in a liquid depend on the density of the liquid?

The pressure is due to the weight of the liquid, which depends on its density.

What is upthrust?

The resultant force due to the difference in pressure between the top and bottom surfaces of an object submerged in a fluid.

What will an object placed in a fluid do if its weight is equal to the upthrust?

It will float.

What will an object placed in a fluid do if its weight is greater than the upthrust?

It will sink.

Why does an object that is more dense than a fluid sink if it is placed in the fluid?

Because its weight is greater than the weight of the fluid displaced, resulting in a greater weight than the upthrust.

Why does an object that is less dense than a fluid float if it is placed in the fluid?

Because its weight is less than the weight of the fluid displaced, resulting in a lesser weight than the upthrust.

Does an object that is partially submerged in a fluid experience a greater pressure on its bottom or top surface?

It experiences greater pressure on its bottom surface.

What is the Earth's atmosphere?

The layer of air that surrounds the Earth.

What is atmospheric pressure caused by?

Air molecules colliding with surfaces.

Why does atmospheric pressure decrease with increased altitude?

The density of the air decreases with altitude, resulting in fewer air molecules and less weight of air above a surface.

How does the height of the atmosphere compare to the radius of the Earth?

The height of the atmosphere is smaller compared to the radius of the Earth.

What are the eight energy stores?

Kinetic, gravitational potential, elastic potential, thermal, chemical, nuclear, magnetic, and electrostatic.

What are the four ways in which energy can be transferred?

Heating, waves, electric current, and mechanically (by forces).

What is a system?

An object or group of objects.

What is a closed system?

A system where no energy can be transferred to or from the surroundings; the total energy in the system stays the same.

What is work done?

Energy transferred when a force moves an object.

What is the unit for energy?

Joules (J).

What is one joule of work?

The work done when a force of 1 Newton causes an object to move 1 meter in the direction of the force.

Describe the energy transfer when a moving car slows down.

Energy is transferred mechanically from the kinetic store of the car to the thermal store of its brakes. Some energy is dissipated to the thermal store of the surroundings.

Describe the energy transfer when an electric kettle is used to heat water.

The electric current in a kettle transfers energy to the heating element's thermal store, which then transfers energy by heating to the thermal store of the water.

Describe the energy transfer when a ball is fired using an elastic band.

Energy is transferred mechanically from the elastic store of the elastic band to the kinetic store of the band; some energy is dissipated to the thermal store of the surroundings.

Describe the energy transfer when a battery-powered toy car is used.

Energy is transferred electrically from the chemical store of the battery to the kinetic store of the toy car; some energy is dissipated to the thermal store of the surroundings.

Describe the energy transfer when a falling apple hits the ground.

Energy is transferred from the kinetic store of the apple and dissipated to the thermal store of the surroundings by sound waves.

What is the unit that represents one joule transferred per second?

Watt (W).

What does a material's thermal conductivity tell you?

It indicates how well the material conducts heat.

Which materials have low thermal conductivity?

Thermal insulators.

Give three factors that determine the rate of thermal energy transfer through a material.

Thermal conductivity of the material, temperature difference, and thickness of the material.

What factors affect the rate of heat loss from a building?

Thickness of walls and roof, thermal conductivity of walls and roof, and the temperature difference between the two sides of the wall/roof.

Define specific heat capacity.

The amount of energy needed to raise the temperature of 1 kg of a material by 1°C.

What is infrared radiation?

A type of electromagnetic radiation.

What is the relationship between the temperature of an object and its emission of infrared radiation?

The higher the temperature of an object, the more infrared radiation it emits in a given time.

What can you tell about an object that absorbs and emits infrared radiation at the same rate?

It is at a constant temperature.

Compare the amount of infrared radiation emitted and absorbed by an object that is increasing in temperature.

More infrared radiation is absorbed than emitted.

What is a black body?

A theoretical object that absorbs 100% of the radiation that falls on it and does not reflect or transmit any radiation.

Name three greenhouse gases.

Water vapor, carbon dioxide, and methane.

What human activities increase the levels of greenhouse gases released?

Deforestation, burning fossil fuels, and livestock farming.

Why do greenhouse gases increase the Earth's temperature?

Greenhouse gases absorb and re-emit radiation from the Earth's surface, trapping heat and increasing the temperature.

What is the difference between distance and displacement?

Distance is a scalar quantity with magnitude only; displacement is a vector quantity with both magnitude and direction.

What is the difference between speed and velocity?

Speed is a scalar quantity with magnitude only; velocity is a vector quantity with both magnitude and direction.

What factors can affect the speed at which someone walks, runs, or cycles?

Age, fitness, terrain, and distance travelled.

What are typical speeds for a person walking, running, and cycling?

1.5 m/s, 3.0 m/s, and 6.0 m/s respectively.

What are typical speeds of a car and a train?

13-30 m/s and 50 m/s respectively.

What is a typical speed for sound travelling in air?

330 m/s.

What is acceleration?

Change in velocity of an object per second.

What is the unit of acceleration?

m/s².

How can an object be accelerating even if it is travelling at a steady speed?

If it is changing direction.

What is happening to an object if it has a negative acceleration?

It is slowing down.

What information does the gradient of the line in a distance-time graph provide?

Speed.

What information does the gradient of the line in a velocity-time graph provide?

Acceleration.

How can the distance travelled by an object be found from its velocity-time graph?

Calculate the area under the graph.

What is the acceleration of a free-falling object due to gravity?

~9.8 m/s².

What is the name for the steady speed a falling object reaches when the resistive force is equal to its weight?

Terminal velocity.

What is the general name for the frictional forces an object experiences when moving through a fluid?

Drag.

In which direction does the drag on an object always act?

In the direction opposite to which it is moving.

What happens to the drag on an object as its speed increases?

The drag increases.

What can be done to reduce the drag on an object?

Streamlining.

What is the name given to the distance a vehicle travels to safely come to a stop after the driver has spotted a hazard?

Stopping distance.

What is thinking distance?

The distance a vehicle travels during the driver's reaction time.

What is braking distance?

The distance a vehicle travels once brakes have been applied.

What is the relationship between stopping distance, thinking distance, and braking distance?

Stopping distance = thinking distance + braking distance.

Does the speed of a vehicle have a bigger effect on braking distance or thinking distance?

Braking distance.

Which distance is proportional to the speed of the vehicle?

Thinking distance.

Which distance increases by an increasing amount as speed increases?

Braking distance.

What are three factors that can affect the braking distance of a vehicle?

Speed, road conditions, condition of tyres and brakes.

What is the definition of one joule of work?

The work done when 1 N of force causes 1 m displacement.

What happens if the braking force used to stop a vehicle is very large?

Brakes may overheat or the car may skid.

What is the law of conservation of momentum?

In a closed system, the total momentum before an event is equal to the total momentum after it.

What does F=ma stand for?

Force acting on an object = rate of change of momentum.

What are examples of everyday safety features which work by increasing the time taken for the change in momentum?

Air bags, seat belts, crumple zones in cars, cycle helmets, crash mats in gyms, cushioned surfaces in children's playgrounds.

What do we mean by inertia?

The tendency of an object to remain in a steady state (at rest or in uniform motion).

What does Newton's First Law say?

An object will remain at rest or in uniform motion unless acted upon by a resultant force.

What is the resultant force on a stationary object?

Zero.

What is the resultant force on an object moving at a steady speed in a straight line?

Zero.

What will an object experience if the resultant force on it is not zero?

It will accelerate.

What is the name of the tendency of an object to remain in a steady state at rest or moving in a straight line at a constant speed?

Inertia.

What forces are balanced when an object travels at a steady speed?

Resistive forces = driving force.

According to Newton's Second Law, what is the acceleration of an object proportional to?

The resultant force acting on it.

According to Newton's Second Law, what is the acceleration of an object inversely proportional to?

The mass of the object.

What is the inertial mass of an object?

How difficult it is to change an object's velocity.

What does Newton's Third Law say?

When two objects interact, they exert equal and opposite forces on each other.

Starting to move, stopping moving, speeding up, slowing down, and changing directions are all examples of which physical process?

Acceleration.

What is a scalar quantity?

A quantity that only has size (magnitude).

What is a vector quantity?

A quantity that has both size and direction.

What is a force?

A push or pull that acts on an object due to the interaction with another object.

Is force a vector or scalar quantity?

Vector.

What is a contact force?

A force when objects are physically touching.

What is a non-contact force?

A force when objects are physically separated.

What is the size of the resultant force on an object if the forces on it are balanced?

Zero.

What is the name for the force acting on an object due to gravity?

Weight.

What instrument can be used to measure the weight of an object?

Calibrated spring-balance (newtonmeter).

What is the centre of mass?

The point through which the weight of an object can be considered to act.

What is elastic deformation?

An object can go back to its original shape and size when deforming forces are removed.

What is inelastic deformation?

An object does not go back to its original shape and size when deforming forces are removed.

How do you find the spring constant from a force-extension graph of a spring?

Find the gradient of the straight line section.

What is the turning effect of a force called?

Moment.

What can you say about clockwise and anticlockwise moments on a balanced object?

They are equal.

How does a lever reduce the amount of force needed to create a particular sized moment?

By increasing the distance from the pivot.