# Investigating Marbles

In this worksheet, students will have to be part of an investigation into the effect of forces on how far a marble rolls.

Key stage:  KS 2

Curriculum topic:   Forces and Magnets

Curriculum subtopic:   Movement on Different Surfaces

Difficulty level:

### QUESTION 1 of 10

Sam, Keira and Erin were doing an investigation to find out about how far a marble travels. They wanted to see whether the surface the marble rolled across made any difference to how far it went. Here is the equipment they used:

In each of the following questions imagine that YOU are part of the team investigating marbles and think about what YOU would do.

Before they begin their investigation to find out which surface is best for marbles, they want to make sure that they are carrying out a fair test.

What is a fair test?

one when everyone has a go

one when they use the same marble each time

one when they use different marbles

Keira asks "Should we push the marble or just let it go down the ramp?"

Erin says "I think we should just let it go down the ramp without a push."

Why do you think Erin's idea is right?

otherwise the marble might break

otherwise the marble might fly off the ramp

otherwise they might push the marble different amounts

Sam, Keira and Erin put the ramp on different surfaces to see which one the marble travels furthest on.

They did the test THREE times and, each time, they added another brick to make the ramp higher.

Which one of the following statements do you think is correct?

it is not a fair test because the higher the ramp, the greater the force on the marble

it is not a fair test because as the ramp gets higher it might topple over

it is a good test because they can tell which height is best

Sam asks "How many goes do you think the marble should have on each surface?"

What do you recommend?

only one

When they had finished running their marble across the different surfaces they drew up a table of their results. Here it is:

Look at the results and decide which surface the marble travelled furthest on.

thick carpet

sandpit

wooden floor

Why do you think that the marble went furthest on that surface?

the wooden floor was smooth and slippery

the thick carpet was warmest

the wooden floor was bumpy

Why do you think that the marble hardly moved at all in the sandpit?

the sand was very smooth

the sandpit was outside

the sand was bumpy and hard to move through

PREDICT what you expect to happen to the distance the marble might travel if the students polished the wooden floor?

the marble would get stuck in the polish

the marble would roll even further

it wouldn't make any difference

• Question 1

Before they begin their investigation to find out which surface is best for marbles, they want to make sure that they are carrying out a fair test.

What is a fair test?

one when they use the same marble each time
EDDIE SAYS
In a fair test, you want to make sure that you only change ONE thing at a time. Here they want to see the effect of different surfaces on how far the marble goes. So that gets changed but the marble, the ramp, the height of the ramp and so on all stay the same.
• Question 2

Keira asks "Should we push the marble or just let it go down the ramp?"

Erin says "I think we should just let it go down the ramp without a push."

Why do you think Erin's idea is right?

otherwise they might push the marble different amounts
EDDIE SAYS
If they pushed the marble it'd be really hard to make sure it always got the same amount of push (force). That would make it an unfair test. So the best thing is to just let it go from the same place - that way it'll be the same force each time.
• Question 3

Sam, Keira and Erin put the ramp on different surfaces to see which one the marble travels furthest on.

They did the test THREE times and, each time, they added another brick to make the ramp higher.

Which one of the following statements do you think is correct?

it is not a fair test because the higher the ramp, the greater the force on the marble
EDDIE SAYS
Remember, they are testing different surfaces, NOT how raising the ramp affects how far the marble goes. So they should leave the ramp alone and just measure how far the marble goes on each surface.
• Question 4

Sam asks "How many goes do you think the marble should have on each surface?"

What do you recommend?

EDDIE SAYS
Imagine it was one go - what if that one go went wrong and the marble fell off the ramp? That's no good, is it? 50 goes would take forever and they don't need that much information. 5 goes will give them the answer they need.
• Question 5

When they had finished running their marble across the different surfaces they drew up a table of their results. Here it is:

Look at the results and decide which surface the marble travelled furthest on.

wooden floor
EDDIE SAYS
You can see that all the results for the wooden floor are over 90cm (that's nearly 1 metre), way above the other two surfaces.
• Question 6

Why do you think that the marble went furthest on that surface?

the wooden floor was smooth and slippery
EDDIE SAYS
When the marble is rolling there is a force called FRICTION pushing against it that will make it slow down and stop. If the surface is smooth (like the wooden floor) that force against the marble is quite small - that's why it went so much further than on the other two (the marble had a MUCH bigger force slowing it down on those ones).
• Question 7

Why do you think that the marble hardly moved at all in the sandpit?

the sand was bumpy and hard to move through
EDDIE SAYS
Sand is made of little grains and the marble pushes some of these out of the way as it rolls. That slows it down quickly and it builds a barrier of sand in front of it to stop it rolling.
• Question 8

PREDICT what you expect to happen to the distance the marble might travel if the students polished the wooden floor?

the marble would roll even further
EDDIE SAYS
If they polished the floor it would become EVEN smoother. That means that the frictional force slowing the marble down would be smaller, so it would go further.
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