# IP2.6.4 Drawing velocity-time graphs © Oxford University Press 2011 Drawing velocity-time graphs.

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IP2.6.4 Drawing velocity-time graphs © Oxford University Press 2011 Drawing velocity-time graphs

IP2.6.4 Drawing velocity-time graphs © Oxford University Press 2011  In the same way that you can record an object’s distance at different times, you can also record an object’s velocity at different times.  You can plot this data on a velocity–time graph. Time is usually plotted on the x-axis and velocity on the y-axis.  The velocity is plotted at different times and the graph can then tell you whether the object is moving forwards or backwards, at what speed and whether it is speeding up or slowing down.

IP2.6.4 Drawing velocity-time graphs © Oxford University Press 2011 This velocity-time graph shows the velocity at different times for a train travelling on a track between two stations. If the object is going steadily faster, the velocity is steadily increasing, and the graph shows a straight line sloping upwards. If an object is moving at a steady (constant) velocity, the line on the graph is horizontal; the velocity is not changing. The greater the velocity the higher the horizontal line. If the object is slowing down steadily, the velocity is steadily decreasing, and the graph shows a straight line sloping downwards. If the object moves backwards, the velocity is negative, and so those graph points will be plotted below the x-axis.

IP2.6.4 Drawing velocity-time graphs © Oxford University Press 2011 We can calculate the acceleration using this formula : Acceleration = Change in velocity Time The units of acceleration are: metres per second / seconds We write this as ‘metres per second squared (m/s 2 ) Change in velocity = 18m/s Time = 15 seconds