FORCES AND MOTION NOTES
 Created by: Bethany Cunningham
 Created on: 270112 19:26
Speed and velocity
Equation:
Distance (m) / (km)
Speed =
Time (s)/(h)
DON'T BE FOOLED BY 1 HOUR AND 30 MINUTES,
THE ANSWER IS 1.5
E.g. Ursain Bolt ran 100 metres in 9.58 seconds.
What was his speed?
= 100/9.58 = 10.4384 m/s
E.g. How quickly would it take him to complete if he ran 100m at a speed of 11.2 m/s
= 100/11.2 = 8.9286 s
Exam hints
 Units for speed NEED to be m/s or km/s
Distance time graphs
The gradient of the graph can be used to calculate the speed at different points
Speed describes how fast an object travels
(the time taken for an object to cover a certain distance)
Velocity
Velocity is speed in a given direction
EXAM TIPS!

 Check the labels > velocity/speed
 The area under the line tells the distance travelled
Acceleration
The change in velocity over time
*If it is a negative number then it is decelarating.*
Forces
Newton's law of motion
 Inertia things like doing what they are already doing
 If the forces on an object are equal, it is either stationary or moving at a constant speed.
Forces are measured in Newtons (N)
Usually the bigger the arrow the bigger the force but obviously on the diagram above it is not drawn to scale
 Forces can change the direction of things
Force = mass x acceleration
(N) = kg x m/s2
Also if the examiner asks to write the equation DON’T write the triangle out.
This is an obvious one but…
Gravity is the force of attraction objects have for each other because of their MASS
The bigger the mass, the bigger attraction
No resultant force equals to terminal velocity
When an object falls the two forces that affect it are:
 Gravity
 Air resistance
So this is the step by step guide that you have to learn:
At first the gravity force is greater than the air resistance force so the object accelerates in…
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