Velocity-Time Graphs

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Velocity-Time Graphs
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Velocity-Time Graphs

• Graphs that represent an objects velocity versus
  its time.
• Time is marked on the horizontal axis and
  velocity is on the vertical.

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Be careful!

• Velocity-time graphs show SPEED.
• A negative y value indicates that the object is
  going in the opposite direction.
• Slope shows ACCELERATION.
• Area under the curve shows DISPLACEMENT.

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Interpreting Velocity-Time graphs

• Horizontal lines show uniform motion (constant
  speed and direction).
• Inclined lines show change in speed or direction,
  or both in other words accelerated motion.

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• Velocity-time graphs can be tricky to interpret
  so lets look at a few examples

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Example A

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Example A

• The car was travelling forward at a steady speed
  of 50 km/h. Then it slowed down to 30km/h as it
  entered a school zone and continued until the end
  of the observations.

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Example B
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Example B

• The car was travelling forward at a steady speed
  of 30 km/h. It slowed to a stop, and stayed
  stopped for a period before it resumed its motion
  forward again. It took more time to speed up
  than to slow down.

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Example C
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Example C

• The car was at rest, then quickly moved backwards
  at a speed of 10 km/h (velocity -10 km/h). The
  car then moved forward, speeding up until it
  reached a constant speed of 40 km/h (velocity
  40 km/h)