Stopping safely
I can apply an understanding of force = change in momentum ÷ time to explain how forces and momentum can be controlled.
Stopping safely
I can apply an understanding of force = change in momentum ÷ time to explain how forces and momentum can be controlled.
Lesson details
Key learning points
- Increasing a stopping force decreases the time it takes a moving object to stop.
- Extending the time it takes to stop reduces the size of the stopping force.
- Many safety devices crumple on impact to increase the time that forces act before stopping a moving object.
Common misconception
Pupils often do not understand clearly what is meant by stopping time and cannot explain why longer stopping times result in smaller forces.
Describe stopping time as the time it takes to stop ‘during which a force is acting’, and provide examples of smaller forces stopping moving objects over longer periods of time than larger forces.
Keywords
Stopping forces - Forces used to bring moving objects to a stop.
Stopping time - The time taken for a moving object to stop.
Momentum - The product of the mass and velocity of a moving object, p = m × v.
Crumple zones - Parts of a car designed to crumple during impacts, increasing the stopping time and reducing the stopping forces.
Airbags - These inflate rapidly in collisions and protect passengers from impacts with hard surfaces.
Content guidance
- Depiction or discussion of sensitive content
Supervision
Adult supervision recommended
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Video
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Starter quiz
6 Questions
displacement -
m
velocity -
m/s
mass -
kg
momentum -
kg m/s
Exit quiz
6 Questions
stopping forces -
Forces used to bring objects to a stop.
stopping time -
The time is takes for an object to stop.
momentum -
The product of mass and velocity of a moving object, $$p = m × v$$.
crumple zones -
Parts of a car designed to crumple and increase stopping time.
airbags -
Inflate in a collision and protect passengers from impacts.
seatbelts -
These stretch to increase stopping times and reduce impact forces.
crumple zones -
These collapse to increase stopping times and reduce impact forces.
air bags -
These inflate to form a protective cushion, increasing stopping times.