Distance–time graphs 18 January 2019 Objective: To use distance–time graphs to analyse the movement of objects.

A man walks 5 kilometers in 25 minutes A dog runs 3 miles at 10mph A boat sails 10 miles in 30 minutes A man walks 20 metres at 10 m/s A fish swims 50 kilometers in 2 hours A cat runs for 10 minutes at 2 minutes per metre

Distances (how far you go) Mile Metre Kilometre Centimetre Millimetre

Time (how long it takes) Seconds Minutes Hours Days Years

Starter – 5 mins Show the students a simple distance–time graph without explanation and ask them to describe what the graph shows. Push them to describe appropriate units for these graphs.

Distance–time graph

How long? How far? Does it speed up? Does it slow down? Does it stop?

If the object speeds up, the line on the graph will get steeper If the object stops, the line will level out If the object slows down, the line will become less steep

What’s the speed? What is the speed of the object between points A and B? time (s) distance (m) 2 1 3 4 5 6 7 8 9 10 20 30 40 50 60 70 A B the object has moved 60 m (70 – 10 ) it took 3 s to move this distance (6 – 3) speed = distance/time = 60/3 = 20 m/s

What’s the speed? How can we work out the average speed of this object between points C and D? time (s) distance (m) 2 1 3 4 5 6 7 8 9 10 20 30 40 50 60 70 A B D the object has moved 70 m (70 – 0 ) it took 9 s to move this distance (9 – 0) speed = distance/time C = 70/9 = 7.8 m/s

Work Complete term 1 worksheet 2 Pupils can act out graphs

Plenary – Sketch the graph on mini whiteboards Two cars moving at a steady speed, car x is faster than car y

Plenary – Sketch the graph on mini whiteboards A car travels through a city centre then stops at the traffic lights, it then joins the motorway.

Plenary – Sketch the graph on mini whiteboards Two runners are running at a steady speed, near the finish line runner A speeds up and overtakes runner B. The race finishes.