Topic 2 : Motion and forces Flashcards
Acceleration due to Gravity:
The acceleration, g, experienced by an object travelling in free-fall. Its value at the surface of Earth is 10 m/s.
Acceleration:
The rate of change of velocity. It can be calculated from the gradient of a velocity-time graph.
Braking Distance:
The distance a vehicle travels under the braking force. This can be affected by adverse road and weather conditions as well as the condition of the vehicle.
Centripetal Force:
The resultant force that acts towards the centre of the circular path of an object travelling with circular motion.
Circular Motion:
The motion of an object travelling in a circle. An object travelling in circular motion is always accelerating due its continual direction change. This means that a centripetal force is always required.
Conservation of Momentum:
The total momentum of a system before an event is always equal to the total momentum of the system after the event.
Displacement:
A measure of how far an object moves in a given direction. It is the straight line between the starting and finishing points and is a vector quantity.
Distance-Time Graph:
plot of how an object’s distance changes over time. The gradient of the graph at any point, equals the object’s speed at that point.
Distance
A measure of how far an object moves. It doesn’t depend on direction and is therefore a scalar quantity.
Free-Fall:
Motion under the force of gravity alone.
Human Reaction Time:
The time it takes for the brain to react to a stimulus.
Typical human reaction times are in the range of 0.2-0.9 seconds.
Inertial Mass:
A measure of how hard it is to change an object’s velocity. It equals the ratio of force over acceleration.
Momentum:
The product of an object’s mass and velocity.
Newton:
Unit of force
Newton’s First Law:
If a stationary object’s resultant force is zero, the object will remain stationary. If a moving object’s resultant force is zero, the object will continue to move at a constant velocity (same speed and direction).
