Speed, Velocity And Acceleration Flashcards
What does speed tell us?
Speed gives us an idea of how slow or fast a body is moving.
What is Velocity
Velocity means the speed of an object and its direction of travel. Quantities such as velocity which have a displacement and a magnitude are vectors.
Speed formula
Average speed= distance moved/time taken
What is acceleration
Something is accelerating if its velocity is changing. Acceleration is a vector.
Average acceleration
Average acceleration = change in velocity / time taken
Acceleration symbols formula
a=(v-u)/t
a is the acceleration
v is the final velocity
u is the initial velocity
t is the time taken
Negative acceleration
A negative acceleration is known as a deceleration or a retardation.
Uniform acceleration
A uniform acceleration means a constant (steady) acceleration.
Why is it average speed?
On most journeys, the speed of a car varies, so the actual speed at any moment is usually different from the average speed.
Gradient of a Distance- time graph
On a distance time graph, the gradient of the line is numerically equal to the speed.
Car travelling at a steady speed
The line rises the same distance on the distance scale for every 1s on the time scale.
Car accelerating
The speed rises, so the car travels further each second than the one before, and the line curves upwards
Car stopped
The distance stays the same so the gradient =0
The gradient of a Speed-time graph
On a speed time graph, the gradient of a line is numerically equal to the acceleration.
Velocity-time graphs
Velocity is speed in a particular direction. Where there is no change in the direction of motion, a velocity-time graph will look the same as a speed-time graph.
