Motion Diagram

This section will explore physical quantities represented by motion diagrams: displacement vs. time, velocity vs. time, and acceleration vs. time. When seeing a motion diagram, thinking about the gradient and area under the curve is essential.

Displacement vs. Time

  • According to the definition of velocity, it is equal to the rate of change of displacement (change in displacement divided by time). Assuming the acceleration is constant and plotting it on a graph, the gradient displacement vs. time equals velocity.
    • The diagram's gradient is equal to velocity.
    • A negative gradient means that the object travels leftward or downward, depending on how the "negative" direction is defined. 
    • A positive gradient means that the object travels rightward or upward, depending on how the "positive" direction is defined. 
  • In Figure (a), a horizontal has a gradient of zero, meaning the object has a velocity is zero. This tells us the object is stationary(not moving).
  • In Figure (b), the linear function's constant gradient tells us that the object travels at a constant velocity.
  • In Figure (c), the linear function's constant gradient tells us that the object travels at a constant velocity.

Velocity vs. Time

  • The gradient of velocity vs. time is equal to acceleration.
  • When considering negative and positive directions, the area under the curve is equal to the total displacement traveled.
  • The sum of areas under the curve without considering direction (negative and positive directions) is equal to the total distance traveled.

Acceleration vs. Time

  • The gradient of an acceleration vs. time graph has no physical meaning. In other words, it does not represent any quantity.
  • The area under curve for an acceleration vs. time graph represents the change in velocity when considering direction, meaning that areas under the x-axis are negative and vice versa.
  • The area under curve for an acceleration vs. time graph represents the change in speed without considering direction, meaning that areas under and above the x-axis are all positive.

Motion Diagram Problems- IB Questionbanks

Motion Diagrma Problems
PDF – 110.1 KB 78 downloads

Quiz

Motion Diagram Quiz 1 - Easy

  • Total Mark: 8
  • Total Time: 12 minutes

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