Motion

Menu Stopping Distances Speed Velocity Distance – Time Graphs Acceleration Velocity – Time Graphs

Stopping distance of vehicles is affected by…. The Thinking Distance And the… Braking Distance

What affects the ‘Thinking Distance? Too much Alcohol Tiredness Thinking Distance Poor Visibility Drugs

What affects the ‘Braking Distance? Icy Roads Wet Roads Braking Distance Driving Too Fast Brakes/ Tyres Worn

Identify whether the ‘Thinking distance’ or ‘Braking distance’ is affected in each case

Stopping Distances Increase alarmingly with extra speed (because velocity is squared!) Kinetic Energy Transferred = Work Done by Brakes ½ mv2 = f x d v = speed of car f = maximum braking force d = braking distance Return to menu

Speed Speed is how fast you are going with NO Regard to Direction d Distance (m) Speed (m/s)= Time (s) d The units of speed are m/s s x t

You can measure your own speed….. Time how long it takes you to run/ walk a set distance record your results in a table and use the equation to calculate your speed Speed = distance/ time

Calculate the speed of this runner He has run 100m in 10 seconds Distance Speed = Time = 100/ 10 = 10 m/s

Calculate the speed of this car It has travelled 6000 metres in 15 minutes Don’t forget to write out your equation, show your workings, convert minutes to seconds and include units!

Calculate the distance this cyclist (Lance Armstrong) has covered He has cycled at 15 m/s for 3 hours Remember time must be in seconds! (Convert hours to seconds) Return to Menu

Velocity Velocity is how fast you are going (with Regard to Direction) Distance (m) Velocity (m/s) = Time (s) d The units of Velocity are m/s v x t Return to Menu

Distance-time graphs 40 30 At Rest 20 10 10 20 30 40 50 Return to Menu Decelerating (In Opposite Direction) Decelerating 40 30 20 10 At Rest Steady Speed Steady Speed (In Opposite Direction) Distance (m) Accelerating 10 20 30 40 50 Time (s) Return to Menu

Questions Distance Time Graphs 80 60 40 20 Questions Distance Time Graphs Distance (metres) 20 40 60 80 100 Time/s What is the speed of the dog during the first 20 seconds? How far is the dog from the start after 60 seconds? What is the speed of the dog during the last 40 seconds? When was the dog travelling the fastest? Return to Menu

Acceleration Acceleration is how fast you are speeding up (or how quickly your velocity is changing) Change in Velocity (m/s) Acceleration (m/s2) = Time (s) V The units of acceleration are a x t (m/s2)

Acceleration = change in velocity Example:-This footballer is about to accelerate! Calculate his acceleration He is initially at rest and within 3 seconds he has reached a velocity of 9m/s Acceleration = change in velocity time = (9m/s – 0m/s) 3s = 3 m/s2

This skier accelerates from 0 to 10m/s in 5 seconds This skier accelerates from 0 to 10m/s in 5 seconds. What is her acceleration?

This motor bike accelerates from 10 to 20m/s with an acceleration of 2m/s2. How long did this take?

A rocket accelerates from rest to 5,000m/s in 2 seconds A rocket accelerates from rest to 5,000m/s in 2 seconds. What is its acceleration? Return to Menu

Calculate the acceleration of this bullet The bullet was initially at rest and reached a velocity of 300m/s in just 0.2 seconds

Velocity - time graphs 40 30 20 10 10 20 30 40 50 Steady Speed Steady Speed Increasing Acceleration Steady Speed Deceleration Velocity (m/s) Acceleration 10 20 30 40 50 Time (s)

Questions velocity Time graphs 120 90 60 30 Questions velocity Time graphs Velocity m/s Time (s) 10 20 30 40 50 How fast was the motor bike going after 10 seconds? What is the acceleration from 20 to 30 seconds? What was the deceleration from 30 to 50s? How far did the motor bike travel in total?

Velocity - time graph for terminal velocity Velocity m/s Parachute has opened Terminal Velocity Hits the ground New terminal velocity reached Time s

Velocity - time graph for a parachutist on the moon (Remember No air!) There is NO terminal velocity The parachutist is experiencing less gravitational force & does not accelerate as fast Velocity m/s Hits the ground (HARD!) Parachute has opened Time s Return to Menu