19122021 Equations of Motion 6 Graphs of Motion

19/12/2021 Equations of Motion 6 - Graphs of Motion Summary Notes page 9. ODU M Ashton 2013

What are we learning today? �How the motion of an object can be represented by a graph. �The three types of motion graph. �How to interpret the three types of motion graph. �How an acceleration-time graph can be drawn using information from a velocity-time graph. 19/12/2021 ODU M Ashton 2013

Speed-time Graphs �You should already know the shapes of the basic speed-time graphs. �Constant speed: speed 0 19/12/2021 ODU M Ashton 2013 time

�Increasing speed: speed 0 �Decreasing speed: speed 0 19/12/2021 ODU M Ashton 2013 time

Tracker Analysis: Motion Graphs of a Bouncing Ball �Draw what you think displacement-time, velocity-time, and acceleration-time graphs will look. �Use Tracker to analyse the motion of a bouncing ball. �Now sketch the actual: �displacement-time �velocity-time, �acceleration-time Motion Grapher 19/12/2021

Activity: 1 Motion L 5 - Graphs of Motion �Displacement-time, velocity-time and acceleration-time graphs can be obtained using a motion sensor. 1. Pasco motion sensors 2. Pasco cars 3. ramp 19/12/2021 ODU M Ashton 2013

Interpreting Graphs �The gradient of a displacement-time graph gives the velocity of the object. �The gradient of a velocity–time graph gives the acceleration of the object. �The area under the velocity–time graph gives the displacement. See Virtual Higher Physics: ODU, Equations of Motion, s-t and v-t Graphs 19/12/2021 ODU M Ashton 2013

SQA 8 19/12/2021 ODU M Ashton 2013

Distance = area under graph = ½ x 240 x 16 + 480 x 15 + ½ x 480 = 13, 440 m 19/12/2021 ODU M Ashton 2013

SQA 9 A car travels along a road. The driver sees traffic lights ahead change from green and starts to brake as soon as possible. A graph of the car's motion is shown. Calculate a) the overall stopping distance. b) the acceleration of the car from the moment the driver applies the brakes. a) Distance = area under graph = 0. 4 x 18 + ½ x 2. 8 x 18 19/12/2021 ODU M Ashton 2013

Drawing a velocity-time graph �It is possible to produce a velocity-time graph to describe the motion of an object. Example �A cyclist travels at a steady speed of 9 metres per second for 6 seconds before decelerating uniformly to a speed of 2 metres per second in 7 seconds. She then travels at this steady speed for a further 5 seconds. 19/12/2021 ODU M Ashton 2013

Drawing an acceleration-time graph from a speed-time graph Example Use the graph below to draw the associated accelerationtime graph. velocity 10 5 0 2 3 4 -3 19/12/2021 ODU M Ashton 2013 10 time

The graph below shows how the acceleration of an object varies with time. The object started from rest. Draw a velocity time graph for the first 10 s of the motion. 19/12/2021 ODU M Ashton 2013

Structured Problems: • page 14, Qs 38 -41. • page 16 Extension Questions 1, Qs E 1 -E 7. 19/12/2021 ODU M Ashton 2013

19/12/2021 ODU M Ashton 2013