Forces & Acceleration
Resultant Force = overall unbalanced force
Any resultant force produces acceleration
Force (N) = Mass (kg) x Acceleration (m/s2)
Force is measured in Newtons (N)
A car travels at a steady speed… the thrust force is equal to the drag force.
This does not necessarily mean that the car is stationary, but it does mean that the car is neither accelerating nor decelerating.
A car accelerates from rest.
The forward thrust is larger than the backward drag.
The car will accelerate in the direction of the greater force, in this case the forward thrust
Velocity & Acceleration
How fast something travels
Speed (metres per second, m/s) = distance travelled (metres, m) time taken (seconds, s)
How fast something travels in a direction
Change in speed in a given time
Acceleration (metres per second squared, m/s2) = change in velocity (metres per second) time taken (seconds, s)
Distance vs. Time Graph
Speed vs. Time Graph
Newtons First Law
Balanced forces = constant velocity
Newtons Second Law
Newtons Third Law
"every action has an equal and opposite reaction"
e.g. a book on a table
The book’s weight (mass x gravity) pushes down on the table
The table pushes back with a reaction force
Size of action (weight) = size of reaction
distance (m) = speed (m/s) x time (s)
Velocity is speed with a direction e.g. 10m/s Northwards
Acceleration (m/s2) = change in speed (m/s) / time taken (s)
Acceleration = (final velocity - initial velocity) / time taken (s) or a = v-u/t
Balanced forces = constant velocity (this can be stationary)
Unbalanced forces (resultant) = change in velocity (+ve / –ve)
Every action force has an equal and opposite reaction force
Force (N) = mass (kg) x acceleration (m/s2)
The difference between opposite forces = resultant force. An object will accelerate / decelerate according to its size