As Fast As You Can:
Speed and Velocity:
- Speed is how fast something is travelling (mph, m/s etc).
- Velocity is how fast something is travelling in a certain direction (50 mph South etc).
- They're both calculated in the same way.
- Average Velocity = Displacement / Time
- Speed cameras can be used to catch speeding motorists.
1) 2 lines are painted on the road.
2) A photo is taken when a car crosses the first line, and another on the second.
3) The photos are then used to determine the cars speed.
Acceleration and Velocity-Time Graphs:
- Acceleration is how quickly the velocity of something is changing.
- It can be a change in speed or a change in direction.
- Acceleration = Change in Velocity/ Time Taken.
- It is measured in m/s².
- Velocity-Time Graphs:
1) Gradient = Acceleration.
2) Flat sections show steady speed.
3) The steeper the line, the greater the acceleration/deceleration.
4) Uphill lines are acceleration.
5) Downhill lines are deceleration.
6) The area under any section of the graph is equal to distance travelled in that time.
7) A curve means changing acceleration.
- Calculating Acceleration, Velocity and Distance from a Graph:
1) Eg. Acceleration = Gradient = Vertical Change / Horizontal Change = 30 / 20 = 1.5m/s².
2) The velocity is found by reading it off the velocity axis.
3) Distance travelled is equal to the area under the graph.
- A force is a push or a pull. Six main forces:
1) Gravity or weight - acts straight downwards.
2) Reaction force from a surface - straight upwards.
3) Thrust / Push / Pull - speeding up
4) Drag / Air Resistance / Friction - slowing down
5) Lift - aeroplane wing etc.
6) Tension - in a rope, cable etc.
- Objects only accelerate in a particular direction if there's an overall force in that direction.
- If the forces on an object are balanced, it won't move.
Friction Forces and Terminal Velocity:
- Friction is always there and effects everything.
- If there is no force pushing something, it will stop.
- Friction acts in the opposite direction to the way an object is moving.
- It occurs between two surfaces.
- In fluids (including the air) it's called drag.
- Drag increases as the speed of…