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Home » Engineering for kids » Bumper Car STEM Challenge

Bumper Car STEM Challenge

Modified: Sep 30, 2022 · Published: Jan 19, 2022 by Emma Vanstone · This post may contain affiliate links · Leave a Comment

Today’s STEM challenge is to design and build a bumper car that will rebound back after a collision with a wall or another mini vehicle.

This car themed STEM challenge is a great hands-on introduction to Newton’s Laws of Motion and a fun engineering and design project too.

Car made from cardboard for a bumper car StEM challenge

Bumper Car STEM Challenge

You’ll need

Balloons

2 wide straws

2 narrow straws

Cardboard

Thick card or 4 round objects such as bottle tops for wheels.

Paper

Glue and tape

Small boxes of plastic water bottle

Elastic bands

Timer – optional

Ramp – optional

play dough, cardboard, straws, scissors and balloons for a bumper car STEM challenge

How to make a basic car

This basic car model can be used for lots of different science and STEM projects. I use the same simple construction for my balloon powered cars too!

Cut out a rectangle from a sheet of cardboard. A box or plastic bottle also works well.

Trim the wider straws so they fit horizontally across the cardboard.

sheet of card with two straws attached reading for a bumper car STEM challenge

Attach the straws to the cardboard with tape or glue. I usually use double sided tape for this part.

Thread the narrower straws through the wide straws and attach the wheels.

Check the car moves smoothly.

Once you’re happy with the basic car you can start adding extra design features.

basic wheels and axels for a car themed STEM project

Bumper car STEM test ideas

Roll a car into a wall at low and high speeds. Measure how far the car rolls backwards or how long it rolls back for.

Roll a car down a ramp into another car or wall.

Another fun idea is to repeat the collision with an egg as a passenger. This can be a boiled egg or if you’re feeling brave a raw egg! Remember to ask a parent first.

The car below has a large padded bumper made from craft sticks, a toilet roll and pom poms for extra cushioning.

Car made from cardboard for a bumper car StEM challenge

This car has two bumpers made from craft sticks and a straw.

bumper car STEM project made using craft sticks

This car has balloon bumpers.

Cardboard car made with balloon bumper for a car themed STEM challenge
Balloon bumpers

Car collision tests

There are several different ways you can test your bumper car.

  • Roll the car down a ramp so it collides with a wall. Record the distance the car rebounds back from the wall or the time it takes for the car to stop moving after impact.
  • Roll the car down a ramp into another test vehicle. This time record the time it takes for each car to stop moving and the distance each car travels.

Questions to ask

Is there a relationship between the amount of rollback and speed of the car when it hits a wall/object?

Does a bigger car roll back for longer?

Newton’s Third Law

Newton’s third law of motion states:

For every action, there is an equal and opposite reaction

Or to put it another way:

When two objects interact, the forces they exert on each other are equal and opposite.

If you think of this in terms of a rocket taking off, it all makes sense.

The downward thrust created by the hot gas rushing out of the rocket is the action and the reaction is an opposite upward thrust forcing the rocket into the air.

diagram of forces acting on a rocket

A rocket will continue moving upwards as long as there is a resultant upwards force. If the upwards thrust force was to stop the resultant force would be downwards.

You can see this in action with our bottle rocket!

Newton’s Third Law and Collisions

In the case of a collision the force of one object on the other is equal in magnitude but opposite in direction. This is why when our bumper car collides with a wall or another vehicle it rebounds backwards.

Something to think about

It’s not quite so simple as two cars rebounding off each other with the same acceleration. Newton’s Second Law has to be considered too!

Newton’s Second Law states that:

Force = Mass x Acceleration

If the two colliding cars have different mass they will have different accelerations after the collision.

Momentum

All moving objects have momentum. Momentum is a vector quantity which means it has size AND direction.

Momentum (kg m/s ) = mass ( kg ) x velocity (m/s )

In a collision the total momentum before and event is the same as after an event. This is called conservation of momentum.

As you can see there’s a lot to learn from two objects crashing into each other!

More STEM Challenges like this

You might also like my crash test eggs activity. We used eggs in this as test passengers!

Crash Test eggs

A film canister rocket or a baking soda rocket is a great way to learn more about Newton’s Third Law.

Finally, try to apply momentum to bouncing balls!

My STEM challenge design template might come in handy too!

I would love to see your crash test bumper cars if you make some!

Bumper cars made from recycled materials for a STEM Challenge

Last Updated on September 30, 2022 by Emma Vanstone

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Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

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