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Differences Between Speed and Velocity

The differences between speed and velocity can be summarised as: Speed depends on the path taken while velocity is independent of path taken. Additionally, an object that makes a round trip, i.e. travels away from its starting point and then returns to the ...

Differences Between Speed and Velocity

The differences between speed and velocity can be summarised as:

Speed

Velocity

1. depends on the path taken

1. independent of path taken

2. always positive

2. can be positive or negative

3. is a scalar

3. is a vector

4. no dependence on direction and so is only positive

4. direction can be determined from the sign convention used (i.e. positive or negative)

Additionally, an object that makes a round trip, i.e. travels away from its starting point and then returns to the same point has zero velocity but travels at a non-zero speed.

Investigation: An Exercise in Safety

The following investigation is an exercise in safety. If you have access to the apparatus, we encourage you to carry out the investigation.

  1. Choose an aim for your investigation from the following list and formulate a hypothesis:

    • Do cars travel at the correct speed limit?

    • Is is safe to cross the road outside of a pedestrian crossing?

    • Does the colour of your car determine the speed you are travelling at?

    • Any other relevant question that you would like to investigate.

  2. On a road that you often cross, measure out \(\text{50}\) \(\text{m}\) along a straight section, far away from traffic lights or intersections.

  3. Use a stopwatch to record the time each of \(\text{20}\) cars take to travel the \(\text{50}\) \(\text{m}\) section you measured.

  4. Design a table to represent your results. Use the results to answer the question posed in the aim of the investigation. You might need to do some more measurements for your investigation.

  5. Complete any additional measurements and write up your investigation under the following headings:

    • Aim and Hypothesis

    • Apparatus

    • Method

    • Results

    • Discussion

    • Conclusion

  6. Answer the following questions:

    1. How many cars took less than \(\text{3}\) \(\text{s}\) to travel \(\text{50}\) \(\text{m}\)?

    2. What was the shortest time a car took to travel \(\text{50}\) \(\text{m}\)?

    3. What was the average time taken by the \(\text{20}\) cars?

    4. What was the average speed of the \(\text{20}\) cars?

    5. Convert the average speed to \(\text{km·h$^{-1}$}\).

This lesson is part of:

One-Dimensional Motion

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