A train and a bridge
An 800 m train passes a 400 m bridge. Change the speed and find how many seconds it takes to cross the bridge completely.
2D
Age 10+10 min
Motion problems
Loading simulation…
Press “Run”. Bodies move by the laws of physics: gravity, friction, elasticity.
What the experiment shows
Time runs from the moment the train's head enters the bridge until its tail leaves it. The red line stands where the head will be at that moment.
How to run it
- Run the scene and compare who reaches the mark and when.
- Enter your answer in the Task panel and press “Check”.
- Change the conditions with the sliders and solve again.
Questions to discuss
- Which quantity is the same for both participants and which one differs?
- How can you check the answer another way?
The science
All motion problems rest on one relation: distance = speed × time. Knowing two quantities, you find the third by division or multiplication.
Try it at home
Measure with steps the way from your door to the street and time an ordinary and a fast walk: work out the speed each time.
What to change in the editor
- Open the example in the editor and put your own numbers into the sliders and the statement.
- Add another participant and a new question to the problem.