Starter quiz
- Izzy rode her bike for 3 hours and travelled 45 kilometres. What was her average speed?
- 10 km/h
- 15 km/h ✓
- 20 km/h
- 25 km/h
-
- Lucas rides his bike for 4 hours with an average speed of 15 km/h. He travelled at a speed of 10 km/h for the first two hours. What speed must he have been travelling at for the last two hours?
- 10 km/h
- between 10 km/h and 15 km/h
- 15 km/h
- higher than 15 km/h ✓
-
- Which of the graphs shows an object moving with increasing speed (accelerating)?
- Andeep ran 20 metres in 5 seconds then slowed down and walked 5 metres in the next 5 seconds. What was his average speed for the first 5 seconds?
- 1 m/s
- 2.5 m/s
- 4 m/s ✓
- 5 m/s
-
- Andeep ran 20 metres in 5 seconds then slowed down and walked 5 metres in the next 5 seconds. What was his average speed for the whole 10 seconds?
- 1 m/s
- 2.5 m/s ✓
- 4 m/s
- 5 m/s
-
Aisha cycles to school three days in a row. Her speeds are shown on the bar chart. What is her average speed for the journey to school?- 2.0 m/s
- 3.7 m/s ✓
- 4.0 m/s
- 5.0 m/s
-
Exit quiz
- Match the key words or phrases to their definitions.
- average speed⇔the total distance travelled divided by the time taken ✓
- instantaneous speed⇔the speed of an object at a particular moment ✓
- dynamics trolley⇔a wheeled object used in motion experiments ✓
- anomalous reading⇔a result which does not fit the pattern of a set of results ✓
- Which of these statements about instantaneous and average speed is correct?
- The instantaneous speed of an object is always less than the average speed.
- The instantaneous speed of an object is always greater than the average speed.
- The instantaneous speed of an object is always the same as the average speed.
- The instantaneous speed of an object can change during a journey. ✓
- The instantaneous speed of an object is constant during a journey.
-
- A student investigates the relationship between the steepness of a ramp and the instantaneous speed of a trolley at the end of the ramp. Which of these are control variables for the investigation?
- The speed of the trolley at the end of the ramp.
- The steepness of the ramp.
- The length of the ramp. ✓
- The distance the speed is measured over. ✓
- The mass of the trolley. ✓
-
- A trolley rolls down a ramp and passes between two markers that are 20 cm apart in a time of 0.25 s. Calculate the speed of the trolley in m/s.
- '0.8 m/s' ✓
- A pupil collects the following set of timing data for a moving object: 0.25 s, 0.23 s, 0.35 s, 0.22 s, 0.21 s. Which calculation should the pupil use to find the mean time?
- mean time = (0.25 + 0.23 + 0.35 + 0.22 + 0.21) ÷ 5
- mean time = (0.25 + 0.23 + 0.22 + 0.21) ÷ 5
- mean time = (0.25 + 0.23 + 0.35 + 0.22 + 0.21) ÷ 4
- mean time = (0.25 + 0.23 + 0.35 + 0.22) ÷ 4
- mean time = (0.25 + 0.23 + 0.22 + 0.21) ÷ 4 ✓
-
- A trolley rolls down a ramp passing between two markers, 0.20 m apart. The following results are collected: 0.17 s, 0.18 s, 0.17 s, and 0.20 s. Calculate the mean instantaneous speed for the trolley.
- 0.18 m/s
- 1.1 m/s ✓
- 1.0 m/s
- 0.35 m/s
- 0.28 m/s
-
Worksheet
Loading worksheet ...
Presentation
Loading presentation ...
Video
Lesson Details
Key learning points
- A dynamics trolley speeds up (accelerates) along the whole length of a steep ramp.
- Instantaneous speed is the average speed over a very short time period.
- Instantaneous speed can be estimated by measuring movement in a small time period.
- Anomalous readings should be repeated and replaced or removed from sets of repeat readings.
Common misconception
When the trolley is released it speeds up quickly at the start and then rolls at a constant speed.
Show a video of an accelerating trolley in slow motion identifying the distance travelled in successive equal intervals of time.
Keywords
Dynamics trolley - A dynamics trolley is a wheeled object used in experiments. It moves very smoothly over flat surfaces.
Average speed - The average speed is the total distance travelled divided by the total time for a journey.
Instantaneous speed - The instantaneous speed of an object is the speed at a particular moment in time.
Anomalous reading - An anomalous reading is a result which is significantly outside the pattern in a set of results.
+