Objective: Understand the difference between speed and velocity Be able to interpret and draw speed/time graphs

Speed tells you how fast you are travelling (it works like the speedometer in a car). It is a scalar quantity. Velocity is the vector equivalent of speed, it tells you how fast you are travelling and in what direction. It can be +ve or –ve.

I walk Eastwards at a constant speed of 4 ms-1 for 3 seconds. I then stand still for 5 seconds before walking Westwards, back towards my starting point at 6ms-1 for 8 seconds. I then stop. Sketch a speed/time graph and a velocity/time graph for the journey. 10 9 8 7 Speed (m/s) 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Time (s)

I walk Eastwards at a constant speed of 4 ms-1 for 3 seconds. I then stand still for 5 seconds before walking Westwards, back towards my starting point at 6ms-1 for 8 seconds. I then stop. Sketch a speed/time graph and a velocity/time graph for the journey. 10 8 6 4 velocity (m/s) 2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 -2 -4 -6 -8 -10 Time (s)

I walk Eastwards at a constant speed of 2 ms-1 for 4 seconds. I then increase my speed at a constant rate for 3 seconds until I am travelling at 10ms-1. I maintain this speed for the rest of the journey. Sketch a speed/time graph for the journey. 10 9 8 7 Speed (m/s) 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Time (s)

Describe what is happening in this journey Find the distance travelled in the 17 seconds shown. What can you tell about the acceleration at various stages of the journey? 10 9 8 7 A B Speed (m/s) 6 E F 5 4 3 2 1 C D 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Time (s)

Describe what is happening in this journey The journey is split into 3 stages, A to B, B to C and C to D. Find the distance travelled over the 17 seconds and the acceleration in each stage. 10 9 8 7 B C Speed (m/s) 6 5 4 3 2 1 D A 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Time (s)

An underground train leaves the station en route to the next station which is 0.8 km away. It accelerates uniformly to its maximum speed and then stays at this maximum speed for 90s before decelerating at a constant speed to stop at the next station. The journey takes 2 minutes, what is the maximum speed? Speed (m/s) Time (s)

From a standing start I walk Eastwards accelerating at a constant rate for 2 seconds until I am travelling at 4ms-1. I maintain this speed for 3 seconds and then decelerate at a constant speed until I am stationary. This takes 4 seconds. I then walk back to my starting position at a steady speed, it takes me 5 seconds. At what speed is my return journey? Sketch a speed/time graph for the journey. Sketch a velocity/time graph for the journey

Look at this velocity time graph. Describe what is happening: a) Between A and B b) Between B and C c) Between C and E d) Between E and F e) Between F and G f) At D Draw the speed/time graph for the same journey. 4 B C 3 2 Velocity (m/s) 1 F G D A -1 -2 -3 E -4 -5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Time (s)

Look at this velocity time graph for a particle What is the displacement of the particle after 11 seconds? What is the displacement of the particle after 14 seconds? How far has the particle travelled in total? 4 A B 3 2 Velocity (m/s) 1 -1 -2 -3 C -4 -5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Time (s)