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Year 9

The force of a floor

I can explain how a floor can support a range of objects with very different weights.

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New
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Year 9

The force of a floor

I can explain how a floor can support a range of objects with very different weights.

Download all resources
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Share activities with pupils
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Lesson details

Key learning points

  1. More force is needed to hold up a bigger mass up in the air.
  2. The bigger the mass on a beam, the more the beam bends.
  3. The more a beam bends, the greater the force it pushes back with.
  4. The bigger the mass on a floor, the more particles in the floor are squashed together.
  5. The more particles in a floor are squashed together, the greater the force they push back with.

Keywords

  • Gravitational force - A gravitational force acts on any object inside a gravitational field.

  • Normal reaction force - When an object rests on a surface, there will be a normal reaction force acting on it.

  • Elastic - Materials are elastic if they return to their original shape when forces are removed from them.

  • Electrostatic force - The force between two electrically charged particles is an electrostatic force.

Common misconception

There is a downwards force on a surface, but no upward force, the surface just gets in the way.

Have pupils describe upward forces they need to exert whilst supporting different sized weights at arms length.


To help you plan your year 9 science lesson on: The force of a floor, download all teaching resources for free and adapt to suit your pupils' needs...

Demonstrate the setup with a ruler and supports before pupils begin the activity. Ensure pupils place the 30 cm ruler behind the metre ruler accurately to measure the bend effectively. Highlight the importance of recording readings carefully as measurements could be as small as millimetres.
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Supervision

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Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Starter quiz

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6 Questions

Q1.
Which word is used to describe the downwards force of an object on a surface it is resting on?
Correct answer: weight
thrust
friction
upthrust
magnetic
Q2.
Which of the following affects the amount of weight of an object on a surface?
the shape of the object
Correct answer: the mass of the object
the surface area of the object
Correct answer: the gravitational field strength
the strength of the surface
Q3.
What word is used to describe a material that returns to its original shape when the forces acting on it are removed?
rigid
plastic
Correct answer: elastic
soft
stretchable
Q4.
What type of electric charge do electrons carry?
north
south
Correct answer: negative
positive
Q5.
What type of force acts between two objects that are electrically charged?
magnetic
gravitational
friction
weight
Correct answer: electrostatic
Q6.
Which of the following correctly describe the structure of an atom?
a small, negatively charged nucleus containing protons and neutrons
Correct answer: a small, positively charged nucleus containing protons and neutrons
a small, nucleus (with no charge) containing protons and electrons
negatively charged protons surrounding a nucleus
Correct answer: negatively charged electrons surrounding a nucleus

Exit quiz

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6 Questions

Q1.
Match the key words with the descriptions.
Correct Answer:elastic,a material that returns to its original shape when forces are removed
tick

a material that returns to its original shape when forces are removed

Correct Answer:gravitational force,a force that acts on any object in a gravitational field
tick

a force that acts on any object in a gravitational field

Correct Answer:normal reaction force,a force that acts upwards when an object rests on a surface
tick

a force that acts upwards when an object rests on a surface

Correct Answer:electrostatic force,a force that acts between electrically charged particles
tick

a force that acts between electrically charged particles

Q2.
Izzy holds a mass stationary in her hand. Which statements are correct?
An image in a quiz
There is no force acting on her hand.
Correct answer: There is no resultant force on the mass.
Correct answer: The upwards force on the mass is equal and opposite to the downwards force.
The downwards force less than the upwards force.
Q3.
What happens to the size of the electrostatic forces between two surfaces when they are pushed closer together?
it remains constant
it decreases
Correct answer: it increases
it becomes zero
Q4.
Some pupils use a plank of wood to build a bridge across a ditch. They walk across the plank one at a time to get to the other side. What happens to the wooden plank as they walk across?
The plank does not bend because it is solid.
Correct answer: The plank will bend slightly as they cross.
Correct answer: The heavier the pupil, the more the plank will bend.
The bridge will bend by the same amount for each pupil.
Q5.
How do the forces between atoms in solids operate?
When the atoms are too close together the forces pull the atoms together.
Correct answer: When the atoms are too close together the forces push the atoms apart.
When the atoms are a little bit too far apart the forces push the atoms apart.
Correct answer: When the atoms are a little bit too far apart the forces pull atoms together.
Q6.
A 5 kg mass is placed on a solid surface. What happens when a second identical mass is placed on top of the first?
Correct answer: The size of force pushing down on the surface increases.
The size of force the surface pushes up with remains the same.
Correct answer: The atoms in the surface are pushed closer together and repel each other more.
The atoms in the surface are pulled further apart and repel each other less.
Correct answer: The surface produces a larger upwards force.
Q2 UYSEG

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