MB Science - 12 - Snowball Slingshot

'Try this' challenge 12: Snowball Slingshot

You will need:

Quick start:

Plastic bottle with tapered neck (a squash bottle is perfect)
Marker pen
Tape
Balloon
Scissors
Some “snowballs” to send flying: cotton wool balls, or scrunched tin foil works perfectly

Genius:

Paper
Colouring pencils/felt tips
Any other decorations to make your launcher as jazzy as possible

What to do:

Before you can start to play, you need to make your Snowball Slingshot.

Draw a circle around the neck of your bottle in marker pen.
Cut along the line you have drawn. To get started you have to stab a hole in the bottle first using the pointy end of your scissors. An adult should definitely do this part.
We’re only using the top of the bottle here, so you can use the bottom part to play ping pong pick up! If you’ve made any sharp or jagged edges with your scissors, cover them up with sticky tape so that your slingshot is safe to hold and use.
Take off the cap and stretch the balloon over the mouth of the bottle. If your balloon bunches up when you do this, gently pull it, so that it’s even all the way round.

Now is the time to test your launcher. Try launching rolled up bits of tin foil or cotton wool balls so your home remains unscathed. And it should go without saying - don’t fire them at each other!

Put your snowball into the bottle, hold onto the neck with one hand and pull the balloon back with the other. Then take aim and release the balloon to shoot snow through the sky.

Challenge your friends and family to see who can shoot the furthest and who has the best aim – put targets on the floor, you can use bowls or boxes and place them wherever you like:

An easy target scores 10 points

Medium target, 20 points

Difficult, 40 points

The competitor with the most points after five launches is the winner. Remember to play n-ice!

Genius challenges:

What happens to the distance when we change the angle we launch the ball at?
What do you think makes a good slingshot?
Can you improve the design of the slingshot at all?

Think about:

1. 1. The shape and size of your projectile
  2. Can you swap the balloon for a different material to launch your projectile?
  3. The size, length and material of your tube
How will you know for sure that you have made the design better?

email your photos/ videos / explanation to trythisathome@mountbatten.hants.sch.uk to get your reward!

What is going on?

Pulling the balloon back stretches it out of shape. When you let go, the balloon snaps back into its original shape, flicking into the snowball. This flicking force is what launches the snowball and sends it flying.

But to win a game of Snowball Slingshot you need to know the best way to hold the tube. The secret is the direction, or angle, that you’re pointing it. This is because from the moment the snowball leaves the slingshot, the force of gravity controls the journey it takes. An object is called a projectile if, once it has been launched, the only force acting on it is gravity. So why does the angle that you fire your snowball make such a difference?

If you point straight upwards and launch, the snowball starts off quickly but the downwards pull of gravity causes the ball to travel slower and slower until it stops going upwards and starts to fall. The snowball speeds up as it falls back down and lands exactly where it started. Launching straight up like this keeps the snowball in the air for the longest time possible, but it hasn’t gone forwards at all, which won’t get you any points.

At the other extreme; when you point straight ahead and launch, we are pointing in the right direction. But because we aren’t firing upwards at all, the snowball doesn’t stay in the air very long so it doesn’t go very far.

When you tilt the tube diagonally upwards and then launch, it’s a compromise between the two and the snowball takes a lovely curved path up and back down to the floor. To get the maximum distance and the most points you should launch diagonally upwards at 45⁰. This angle is exactly between straight up and straight forwards and is the perfect balance between the two.

Knowing the physics behind snowball (or any projectile) launching should give you the secret to winning a game of snowball slingshot. It’s up to you whether you decide to tell your family and friends!