Speed can be measure in.....
[3]

#metres per second
#kilometres per hour
#miles per hour

The faster the speed of an object:
[2]

the greater the distance it travels in a particular time
the shorter the time it takes to travel a particular distance

How to calculate speed?

distance (m)
speed = ____________________ (m/s) time (s)

Why is the average speed used?

The speed may change over a given distance, so an average distance over the whole journey is used

How to work out average distance?

Distance = (u + v) * t

2

Example question:
Calculate the distance a car travels in 90 minutes if it's travelling at a constant speed of 80 km/h ?

distance = speed * time
= 80 km/h * 1.5 hours
= 120 km

How do speed cameras work?

They generally take 2 pictures of a vehicle a certain amount of time apart. the position of the vehicle in relation to the distance markings on the road in the 2 pictures can be used to calculate the vehicle's speed

What is the formula for measuring the speed of a vehicle on a speed camera?

speed of car = distance travelled between pictures / time taken between 1st and 2nd picture

(Distancetime graphs) The steeper the gradient....

the greater the speed

distance  time graphs) a straight diagonal line shows...

a constant speed

(distancetime graphs) a straight horizontal line shows.....

No movement (stationary)

(distancetime graphs) a steeper diagonal line means....

an increase in speed (object is going faster than it was before)

(distancetime graphs) a diagonal line going downwards means....

object is going backwards

How do you work out the speed of an object on a distancetime graph?

take any 2 points on the graph and read off the distance travelled for that part of the journey and the time taken to get there

The acceleration / deceleration of an object is..... ?

the change in speed per second

How do you measure acceleration and deceleration?

acceleration = metres / second squared
deceleration = metres / second squared

How do you work out the acceleration of a moving object?

acceleration = (final velocity  initial velocity) / time

Example question: A car accelerates at 1.5 m/s2 for 12 seconds.
Calculate the change in speed of the car

change in speed = acceleration * time taken
=1.5 m/s2 * 12
= 18 m/s

(speedtime graphs) a horizontal line means...

No acceleration (0 m/s2)

(speedtime graphs) a positive diagonal line shows....

acceleration

(speedtime graphs) a negative diagonal line shows..

deceleration

(speedtime graphs) the area underneath the speedtime can be used to measure....

distance travelled

How would you calculate the total distance travelled on a speedtime graph?

Cut the graph into triangles and rectangles, then find the area for each shape and add them all up. REMEMBER!
area of rectangle = width * height
area of a triangle = 1/2 * base * height

What is Force measured in?

Newtons

Forces can cause objects to....?

accelerate

Weight causes an object to have.... ?

gravity
(weight can also be called gravity)

How does friction affect a car?

it slows it down

What happens when a sky diver opens up a parachute midjump?

Air resistance  Air resistance causes the skydiver to slow down A LOT when the parachute opens.

What happens to a skydiver midjump when air resistance and weight are balanced?

they stay at a constant speed

if an unbalanced force acts, the acceleration of an object will depend on: ?
[2]

#the force applied to the object
#the mass of the object

more force = ... ?

= more acceleration

more mass = ... ?

= less acceleration

What is the formula for the relationship between force, mass and acceleration
force (N) = .... ?

= mass (kg) * acceleration (m/s2)
