IGCSE chapter 15 Speed time grpahs.pptx

IGCSE chapter 15 Speed time grpahs

1. Grade 9 B/C 14.3 Speed Time Graphs Date: 10/16/2022

2. Starter 10/16/2022

3. Speed/Velocity- Time Graphs!

4. What’s the difference between? Distance and displacement Speed and velocity

5. What is speed? Speed is a measure of how far an object moves in a given time. This jet is travelling at 350 m/s. This means the jet travels 350 metres every second. This car is travelling at 60 mph. This means the car travels 60 miles every hour.

6. The speed of an object does not depend on the direction in which it is travelling. The velocity of an object is the speed and direction in which it is moving. The car is travelling north with a velocity of 10 m/s. How is velocity different to speed? As the car goes round the corner, the speed of the car remains constant but the velocity changes.

7. Speed time graphs Lesson Objectives 1. Interpret Speed–time graphs 2. Calculate acceleration. 10/16/2022

8. Introduction. 10/16/2022

9. The acceleration of an object is a measure of how quickly its velocity changes. A train accelerates in a straight line from rest. As it does, its velocity increases. The brakes on this motorcycle are causing it to slow down. This is negative acceleration or deceleration . What is acceleration?

10. Car is accelerating here – the speed is increasing. The car is going at constant speed – acceleration is zero. The car is decelerating here – or slowing down The car is at rest here – with zero speed

11. 10/16/2022 Time in Sec Distance in Km 5 10 15 20 40 20 60 80 Time Speed 5 10 15 20 2 1 3 4 Speed = Distance /time Speed = 70/20 = 3.5 km/sec What does this show? Horizontal Line Shows Constant speed 3.5 x 20 = 70 Km

12. Activity 1... 10/16/2022

13. What Graphs says: Choose correct Words 10/16/2022

14. Objective 2 10/16/2022 Calculate Acceleration

15. Acceleration and deceleration Speed-time graphs show speed on the vertical axis and time on the horizontal axis. The gradient of a speed-time graph represents acceleration . Acceleration represents in Metres per second square can be written as m/s2 or ms−2. A negative gradient shows the rate of “slowing down” or deceleration . 10/16/2022

16. 10/16/2022 Time (sec) Speed (m/sec) 5 10 15 20 2 1 3 4 Acceleration Distance time graph for the cyclist. 5 6 7 The Rate of increase of speed is the acceleration. Acceleration = gradient =   Acceleration = = m/sec 2  

17. Activity 2. Calculate acceleration and deceleration 10/16/2022 Acceleration = gradient =   For Line 1 Acceleration = m/s2   For Line 2 Constant speed / acceleration = m/s2   For Line 3 deceleration = m/s2  

18. 10/16/2022 Plenary Summarize the Topic

19. What happened to the bicycle at seconds?   What happened to the bicycle between and seconds?   For how long was the bicycle stationary? For how long was the bicycle going at a speed of ?   What was the speed of the bicycle after seconds?   How many times during the journey did the bicycle move at constant speed? Speed-Time Graphs Spider 1 The speed-time graph shows the journey made by a bicycle.

20. What happened to the bicycle at seconds?   What happened to the bicycle between and seconds?   For how long was the bicycle stationary? For how long was the bicycle going at a speed of ?   What was the speed of the bicycle after seconds?   How many times during the journey did the bicycle move at constant speed? It stopped suddenly   seconds   It decelerated then stopped times   seconds   Speed-Time Graphs Spider 1 - Answers The speed-time graph shows the journey made by a bicycle.

21. H.W. &TDN H.W. TDN: Speed Time Graph