Speed, Velocity And Acceleration Flashcards
Define speed, displacement and velocity
Speed: change of distance per unit of time
Displacement: distance in a given direction
Velocity: change of displacement per unit time
What is the equation field an object travelling distance,s in time,t at a constant speed?
v= s/t
What is the equation for an object travelling on a circle of radius, r at a speed?
v= 2pir/ T
Where T is the time taken to move around once
What is the gradient of the line in distance-time graphs?
The speed of the object= distance travelled/ time taken= gradient of the line
Define the term ‘constant velocity’
An object that moves at the same speed without changing its direction of motion
Explain Displacement-time graphs
An object travelling along a straight line has two possible directions of motion which can be distinguished as positive or negative (in opposite directions)
A car maker wants to compare the performance of a new model with the original model. To do this, the velocity of each car is measured on a test track. Each vehicle accelerates as fast as possible to top velocity from a standstill. The results are listed in Table 1.
Time 0 2 4 6 8 10
Old 0 8 16 24 32 32
Model
New 0 10 20 30 30 30
Which car accelerates the fastest?
Te old model took 8s to reach its top velocity of 32ms^-1. Its velocity must have increased by 4.0 every second when it was accelerating.
The new model took 6s to reach its top velocity of 30ms^-1. Its velocity must have increased by 5.0 every second.
The velocity of the new increases at a faster rate. Therefore the acceleration is greater.
Define acceleration
Change of velocity per unit time.
Measured in ms^-2
It’s a vector quantity
Deceleration values are negative: velocity decreases with respect to time
Define uniform acceleration.
Where the velocity of an object moving along a straight line changes at a constant rate.
What would the equation be for an object that accelerates uniformly from velocity, u to velocity, v in time, t along a straight line?
Acceleration,a, of the object= change of velocity/ time taken= v-u/t
Define non-uniform acceleration.
The direction of motion of an object changes, or its speed cahnges at a varying rate.
How to find the acceleration from a velocity-time graph at a point
The gradient of the tangent at a point= height of gradient triangle/ base of gradient triangle
What is the gradient of a velocity-time graph?
The acceleration
What are the four equations for Constant acceleration?
v= u+ at
s= 1/2 (u+v)t
s= ut +1/2at^2
v^2 = u^2 +2as
