Forces and their effects

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Forces and their effects

• W Richards
• The Weald School

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What is a force?
A force is a push or a pull. Some common
examples
___ ________ (drag) acts against anything
moving through air
________ pulls things downwards
_____ acts against anything moving
______ keeps things afloat
Words upthrust, air resistance, friction, weight
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Balanced and unbalanced forces
Reaction
Consider a camel standing on a road. What forces
are acting on it?
These two forces would be equal we say that
they are BALANCED. The camel doesnt move
anywhere.
Weight
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Balanced and unbalanced forces
Reaction
What would happen if we took the road away?
Weight
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Balanced and unbalanced forces
What would happen if we took the road away?
The camels weight is no longer balanced by
anything, so the camel falls downwards
Weight
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Balanced and unbalanced forces
What would happen if we took the road away?
The camels weight is no longer balanced by
anything, so the camel falls downwards
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Balanced and unbalanced forces
1) This animal is either ________ or moving with
_______ _____
2) This animal is getting ________
4) This animal is also either _______ or moving
with ________ ______..
3) This animal is getting _______.
Words - Stationary, faster, slower or constant
speed?
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Weight and Mass
The MASS of an object is a measure of how much
stuff it contains. The WEIGHT of an object is
the amount of force that pulls it downwards due
to gravity.
1 Kg
This object has a MASS of 1Kg
and a WEIGHT of 10N
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Floating
Whether or not an object will float depends on
its DENSITY. For example
The metal block will ____ because it is ______
dense than water
The wooden block will ____ because it is ______
dense than water
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Friction

• What is friction?
• Give 3 examples where it is annoying
• Give 3 examples where it is useful
• What effect does friction have on the surfaces?

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Stopping a car
Too much alcohol
Tiredness
Too many drugs
Poor visibility
Wet roads
Icy roads
Tyres/brakes worn out
Driving too fast
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Distance-time graphs
40 30 20 10 0




Distance (metres)
Time/s
20 40 60 80 100
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40 30 20 10 0




Distance (metres)
Time/s
20 40 60 80 100

1. How far had the object gone after 20 seconds?
2. How far had the object gone after 60 seconds?
3. When is the object standing still?
4. When was the object travelling the fastest?