# Make a marvellous marble runner

What’s happening?

Once you let it go at the top, your marble will keep rolling unless something stops it. This could be the floor, a container that catches your marble, or a dead end on your run.
As it is rolling, your marble will accelerate. In physics acceleration is more than just an increase in speed. It is a change is something’s velocity. Velocity is the speed of something travelling in a particular direction, and you could draw that movement as an arrow. Any change in the speed or direction of something will result in its acceleration. This could be getting faster, slower or changing direction.
How fast your marble goes is due to the combination of gravity pulling it downward and friction slowing or stopping its fall. The steeper your slope the more that gravity acting on the marble can overcome friction, and your marble rolls faster.
The fastest your marble will move is when it is in freefall. In freefall, gravity speeds the marble up, and the only thing slowing it down is a tiny bit of friction from the air.

Applications

This science is extra fun on a waterslide. When you are on a waterslide, gravity is pulling you down and friction slows you down. The less friction there is, the faster you will go. On a waterslide, water is a lubricant as it reduces the friction between you and the slide.
On the downhill double dipper, one of the world’s fastest waterslides that is 15 metres high and 60 metres long, you can reach speeds of up to 40 kilometres per hour.
The same water park has a freefall where you can fall at 96 kilometres per hour!

This week, guest writer Beth Askham explains how you can make an exciting course for a marble to whiz along, turn and fall downwards.

You will need

• Milk containers
• Cardboard and paper
• Scissors
• A flat board to work on, about one metre by one metre in size (we used a fridge door, which worked well)
• Strong sticky tape
• Marbles
• Decoration like contact, paints and bells
• Old plastic bottles or paper to make funnels
• A stopwatch

What to do

1. Cut up your milk containers to make runners for your marble. Use the corners of the container as channels for your marble to run down.
2. You can also use cardboard folded into a channel to make your runners.
3. Tape the runners onto your board so you have a good channel for the marble to run down.
4. Start at the top of the board where you plan to let your marble go.
5. Create a series of slopes and obstacles that your marble can run down until it reaches the bottom.
6. You can make pipes, tunnels and funnels for your marble by rolling paper into a tube or funnel.
7. You can make free fall drops by cutting holes in your runners for the marble to fall through.
8. You can add bells and spirals to make the run more adventurous.
9. Time how fast it takes for your marble to run from the top to the bottom of the run.
10. Try to make the marble go faster using the same number of runners. What makes it go faster? Does a bigger marble go faster down your run than a smaller marble?
 What you need Making your channels from cardboard containers Stick your run to a solid surface. The marble changes direction and accelerates