C3 - Distance and Speed Flashcards
How’s a displacement time graph plotted?
Displacement along y axis
Time along x axis
Constant gradient shows constant velocity
Gradient shows velocity
What’s acceleration and how’s it calculated?
a = (v - u)/t
Acceleration of an object is the rate of change of velocity in ms-2.
How is a velocity time graph plotted?
The gradient shows acceleration.
V along y axis
t along x axis
The area beneath shows distance travelled.
What are the suvat equations?
v = u + at
s = ut + 1/2 at2
s = 1/2 (u + v) t
v2 = u2 + 2as
What is reaction time?
Reaction time = thinking distance / speed
What’s stopping distance?
Thinking distance + braking distance
What are facts of projectile motion?
Assuming no air resistance:
- the vertical velocity changes due to acceleration of free fall
- vertical displacement and time of flight can be calculated using equations of motion
- horizontal velocity remains constant
Why does horizontal velocity remain constant in projectile motion?
The acceleration of free fall is vertically downwards.
The component of this acceleration in the horizontal direction is zero.
Horizontal acceleration = g Cos 90 = 0
Therefore horizontal velocity is unaffected by the fall.
How is a distance time graph plotted?
Distance along y axis
Time along x axis
Speed is the gradient of the d-t graph
Constant speed is shown by a straight line
Explain why velocity of an object may be changing even though it’s speed it constant:
It is constantly changing direction.
Why would the distance travelled by a braking car be greater when travelling down a slope?
There is a component of weight of the car acting down the slope / a component of weight against resistance.
Net force is less.
What is acceleration?
The rate of change of velocity
Define velocity
The rate of change of displacement
