CAIE Physics IGCSE Topic 1: Motion, Forces and Energy Flashcards

Vocabulary definitions for CAIE Physics IGCSE Topic 1, covering physical quantities, motion, mass, weight, density, forces, momentum, energy, work, power, and pressure.

Analogue device

A measuring device that requires the user to read from a scale to obtain the measurement.

Digital device

A measuring device that displays the measurement on a display, rather than requiring the user to read from a scale.

Magnitude

A measure of size.

Micrometre screw gauge

A measuring implement used to accurately measure very small distances.

Pendulum

A weight suspended from a pivot, that swings freely.

Resultant vector

A single vector with the same effect as the sum of all the individual vectors.

Scalar

A quantity with magnitude only.

Vector

A quantity with magnitude and direction.

Volume

The amount of space that a substance or object occupies.

Acceleration

When an object’s speed is changing; represented by a non-zero gradient on a speed-time graph. Defined as the rate of change of velocity.

Acceleration of free fall

The approximately constant acceleration ($9.8\,m/s^2$) with which objects free fall when close to the earth.

Air resistance

A force opposing an object’s direction of motion through air, caused by air particles colliding with the object.

Average speed

Calculated by dividing the distance travelled by the time taken.

Deceleration

Negative acceleration.

Distance

A measure of how far an object moves; it is a scalar quantity.

Distance–time graph

A plot of how an object’s distance changes over time, where the gradient equals the object’s speed.

Displacement

A measure of how far an object moves in a certain direction, calculated as the difference between final and initial readings; it is a vector quantity.

Free fall

Motion under the force of gravity alone, without air/liquid resistance.

Liquid resistance

A force opposing an object’s direction of motion through liquid, caused by liquid particles colliding with the object.

Speed

A measure of the rate of change of distance; it is a scalar quantity.

Speed–time graph

A plot of how an object’s speed changes over time; the gradient equals acceleration and the area under the graph equals distance travelled.

Terminal velocity

The constant speed achieved by an object falling through a gas or liquid.

Gravitational field

A region where a mass will experience gravitational force.

Velocity

The speed in a given direction; it measures the rate of change of displacement and is a vector quantity.

Balance

A piece of apparatus that can compare different weights and masses.

Gravitational field strength

The amount of gravitational force (weight) acting per unit of mass; on Earth it is $9.8\,N/kg$ (equivalent to acceleration of free fall g).

Mass

A measurement of how much matter is in an object; the property of an object that resists change in motion; it is a scalar quantity.

Weight

The gravitational force that acts on an object with mass; equal to the product of mass and gravitational field strength; it is a vector quantity.

Density

The mass per unit volume of an object.

Elastic solid

Objects that can be deformed when force is applied and return to their original shape and size when the force is removed.

Extension

The lengthening of an object as a result of applied force.

Load-extension graphs

A graph showing how the extension of an object varies with the force (load) applied.

Friction

A resistive contact force that acts to oppose the relative motion between two surfaces.

Limit of proportionality

The point beyond which extension is no longer directly proportional to the force applied to an elastic object.

Resultant force

A single force with the same effect as the sum of all individual forces acting on an object, considering direction.

Spring constant

A measure of a spring’s stiffness; higher values result in smaller extension for a given force.

Equilibrium

A state where an object has zero resultant force and zero resultant moment.

Moment of a force

The turning effect of a force, equal to the product of force magnitude and the perpendicular distance from the pivot.

Perpendicular distance

The shortest distance from the line of action of a force to the pivot point.

Pivot point

The point which an object can rotate about.

Centre of gravity

The single point through which all the mass of an object can be said to act.

Line of action of weight

A line geometrically representing where the force of weight acts on an object.

Plane lamina

A body whose mass is concentrated in a single plane.

Plumb line

A piece of thread used in experiment to measure the centre of gravity.

Stability

A measure of the likelihood of an object toppling; unstable if the line of action of weight lies outside the base.

Conservation of momentum

The total momentum of a system before an event equals the total momentum after the event.

Impulse

The change of a system’s momentum resulting from a force acting over a period of time.

Momentum

The product of an object’s mass and velocity.

Chemical energy

A store of energy found in items such as batteries, fuels and food.

Elastic potential (strain) energy

The store of energy contained in stretched or compressed objects.

Electrical current

A flow of electric charge in a circuit.

Flow diagram

A diagram demonstrating the flow of energy during an event or process.

Gravitational potential energy

Energy store of raised matter; proportional to mass, distance raised, and gravitational field strength.

Internal energy

Energy associated with the random, disordered motion of molecules.

Kinetic energy

Energy store of moving matter; proportional to mass and the square of velocity.

Nuclear energy

Non-renewable energy stored in the nuclei of radioactive isotopes, released via nuclear fission.

Principle of conservation of energy

Law stating energy can be transferred, stored or dissipated but never created or destroyed.

Sankey diagram

A diagram showing energy flow that differentiates useful output and waste energy with proportional amounts.

Work done

Occurs when a force causes an object to move; equal to the product of distance and the force magnitude in the direction of motion.

Efficiency

The ratio of useful output energy transfer to total energy input; cannot exceed $100\%$.

Geothermal energy

Renewable energy from thermal energy below the Earth's surface converted to electrical energy.

Hydroelectric power

Renewable energy from water stored at height turning a turbine and generator.

Nuclear fission

Splitting a single heavy nucleus into two lighter nuclei, releasing energy.

Nuclear fusion

Making a single heavy nucleus from two lighter nuclei.

Renewable energy resource

An energy resource that can be replenished whilst it is being used.

Solar energy

Renewable energy generated by converting sun energy into electricity, usually using solar panels.

Tidal energy

Renewable energy generated by trapping water at high tide and releasing it through a turbine.

Wind energy

The process of creating electricity using the wind.

Power

The rate at which energy is transferred or work is done; calculated as work done divided by time taken.

Normal

Acting at a right angle to a boundary or surface.

Pressure

The force acting perpendicular to a surface, per unit area.