Edexcel GCSE Physics Paper 1

• acceleration


  A measure of how quickly the velocity of something is changing. It can be positive if the object is speeding up or negative if it is slowing down. It is a vector quantity.
• displacement


  The distance travelled in a particular direction. It is a vector, distance is not.
• distance

  How far something has travelled. It is a scalar, and has no direction.
• force


  At the simplest level it is a push, pull or twist. When they act on an object they can cause it to accelerate. It is a vector quantity.
• magnitude


  The size of something, such as the size of a force or the measurement of a distance.
• mass


  A measure of the amount of material that there is in an object. It is a scalar quantity.
• momentum


  A measure of motion, mass multiplied by velocity. It is a vector quantity.
• scalar quantity.


  A quantity that has a magnitude (size) but not a direction. Examples include mass, distance, energy and speed.
• speed


  A measure of the distance an object travels in a given time. Usually measured in metres per second (m/s). It is a scalar quantity.
• vector quantity

  A quantity that has both a size and a direction. Examples include force, velocity, displacement, momentum and acceleration.
• velocity

  The speed of an object in a particular direction. Usually measured in metres per second (m/s). It is a vector, speed is not.
• weight


  The force pulling an object downwards, it depends upon the mass of the object and the gravitational field strength. It is a vector.
• average speed


  The speed worked out from the total distance travelled divided by the total time taken for a journey.
• distance/time graph


  A graph of the distance travelled against time for a moving object. The gradient of the line gives the speed.
• instantaneous speed


  The speed at one particular moment in a journey.
• gradient


  A way of describing the steepness of a line on a graph in numbers. It is calculated by taking the vertical distance between two points and dividing by the horizontal distance between the same two points.
• deceleration


  When an object is slowing down.
• velocity/time graph

  A graph of velocity against time for a moving object. The gradient of a line on the graph gives the acceleration and the area under the graph gives the distance travelled.
• acceleration


  A measure of how quickly the velocity of something is changing. It can be positive if the object is speeding up or negative if it is slowing down.
• balanced forces


  When the forces in opposite directions on an object are the same size so that there is a zero resultant force.
• resultant force


  The total force that results from two or more forces acting upon a single object. It is found by adding together the forces, taking into account their directions.
• scalar quantity


  A quantity that has a magnitude (size) but not a direction. Examples include mass, distance, energy and speed.
• speed


  How fast something is moving. Often measured in metres per second (m/s), miles per hour (mph) or kilometres per hour (km/h).
• unbalanced forces


  When the forces in opposite directions on an object do not cancel out, to there is a non-zero resultant force.
• vector quantity

  A quantity that has both a size and a direction. Examples include force, velocity, displacement, momentum and acceleration.
• velocity

  The speed of an object in a particular direction. Usually measured in metres per second (m/s).
• centripetal force


  A force that causes objects to follow a circular path. The force acts towards the centre of the circle.
• mass


  A measure of the amount of material there is in an object. The units are kilograms (kg).
• weight


  The force pulling an object downwards. It depends upon the mass of the object and the gravitational field strength. The units are newtons (N).
• gravitational field strength


  A measure of how strong the force of gravity is somewhere. It is the force on a 1 kilogram mass, so the units are newtons per kilogram (N/kg).
• inertial mass


  The mass of an object found from the ratio of force divided by acceleration. The value is the same as the mass calculated from the weight of an object and gravitational field strength.
• action-reaction forces


  Pairs of forces on interacting objects. They are always the same size, in opposite directions, and acting on different objects. They are not the same as balanced forces.
• balanced forces


  Forces acting on the same object. They are always equal, in opposite directions, and always act on the same object. They do not have to be the same type of force. An object acted on by these forces will not change the way it is moving..
• equilibrium


  When a situation is not changing because all the things affecting it balance out.
• conservation of momentum


  The total momentum of moving objects before a collision is the same as the total momentum afterwards, as long as no external forces are acting.
• momentum


  The mass of an object multiplied by its velocity. It is a vector quantity, with units kilogram metres per second (kg m/s).
• thinking distance


  The distance travelled by a vehicle while the driver reacts.
• braking distance


  The distance travelled by a vehicle while the brakes are working to bring it to a halt.
• stopping distance


  The distance in which a car is brought to a halt, which is the sum of the thinking and braking distances.
• reaction time


  The time taken to respond to a stimulus.