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1 1 KS3 SCIENCE - PHYSICS KS3 SCIENCE - PHYSICS Velocity & Acceleration Velocity & Acceleration

VELOCITY 2 2

3 3 “Velocity” is the same thing as speed - it measures how fast something is moving “Velocity” is the same thing as speed - it measures how fast something is moving

VELOCITY 4 4 Velocity or speed is the distance travelled in a given period of time, or Velocity = Distance Time Velocity or speed is the distance travelled in a given period of time, or Velocity = Distance Time

VELOCITY 5 5 For example, if a helicopter travels 300 km in 2 hrs it travels at an average speed of 150 km per hr For example, if a helicopter travels 300 km in 2 hrs it travels at an average speed of 150 km per hr

ACCELERATION 6 6

7 7 “Acceleration” is when an object moves at an increasing speed, getting faster and faster as it goes “Acceleration” is when an object moves at an increasing speed, getting faster and faster as it goes For example a space craft does not take off at a steady speed, it gets faster and faster For example a space craft does not take off at a steady speed, it gets faster and faster

ACCELERATION 8 8 Acceleration is how quickly you are speeding up Acceleration = Change in Velocity Time Acceleration is how quickly you are speeding up Acceleration = Change in Velocity Time

ACCELERATION 9 9 For example, if a plane takes 100 seconds to reach a speed of 100 m per second, its speed increases by 1 m per second each second For example, if a plane takes 100 seconds to reach a speed of 100 m per second, its speed increases by 1 m per second each second So acceleration is 1 m per s per s or 1 m/s 2 So acceleration is 1 m per s s or 1 m/s 2

DISTANCE-TIME GRAPHS 10

11 The 2 p.m. train runs at 100 kph from London to Birmingham, then 60 kph to Manchester, then 90 kph to Newcastle The 2 p.m. train runs at 100 kph from London to Birmingham, then 60 kph to Manchester, then 90 kph to Newcastle DISTANCE-TIME GRAPHS

12 The 2 p.m. train runs at 100 kph from London to Birmingham, then 60 kph to Manchester, then 90 kph to Newcastle The 2 p.m. train runs at 100 kph from London to Birmingham, then 60 kph to Manchester, then 90 kph to Newcastle Distance from London Km Time DISTANCE-TIME GRAPHS

Birmingham 13 Distance from London Km Time Manchester Newcastle On a distance- time graph the steepness shows how fast distance is changing, i.e. the speed On a distance- time graph the steepness shows how fast distance is changing, i.e. the speed DISTANCE-TIME GRAPHS

VELOCITY-TIME GRAPHS 14

VELOCITY-TIME GRAPHS 15 Suppose that a boat is rowed along a river at varying speeds Suppose that a boat is rowed along a river at varying speeds

VELOCITY-TIME GRAPHS 16 Suppose the crew warm up, row steadily, then ease up Suppose the crew warm up, row steadily, then ease up

VELOCITY-TIME GRAPHS 17 A graph of speed against time would look like this A graph of speed against time would look like this Velocity km/hr Time hrs

VELOCITY-TIME GRAPHS 18 Velocity km/hr Time hrs On a velocity-time graph, the steepness shows how fast speed is changing, i.e. the acceleration On a velocity-time graph, the steepness shows how fast speed is changing, i.e. the acceleration Warm-up Steady Ease-up