Transcript 5. Momentum - science

18 July 2015
Momentum
Objectives
Be able to describe what momentum is and be able to
calculate it using the equation.
HSW: AF5 – Working critically with evidence
Used before in: 3 – kinetic energy
Will use again in:
PLTS: Self-managers – organise own time.
Used before in: Science A
Will use again in:
Keywords: mass, velocity, m/s, kg, scalar, vector,
momentum, kgm/s, inertia
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Outcomes
• ALL MUST be able to describe momentum
in words.
• MOST SHOULD know the equation for
momentum and be able to use it.
• SOME COULD be able to rearrange the
equation for momentum and describe
momentum as a vector quantity.
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What is momentum?
• http://www.youtube.com/watch?v=y2Gb4N
Iv0Xg
• Watch the clip and the demonstration from
your teacher and then write a description
in your own words:
• Momentum is…
• The factors that affect momentum are…
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What is momentum?
All moving objects have momentum. This is a measure of
how difficult it is to stop a moving object.
If these two cars have the
same mass but one is
quicker than the other, which
has the most momentum?
The faster car.
If both cars travel at the same velocity, but one is full with
luggage and the other is empty, which will have the most
momentum? The heavier car.
The bigger an object is and the faster it moves, the more
momentum it will have and the more difficult it will be to stop.
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How is momentum calculated?
The momentum of an object can be calculated using this
equation:
momentum = mass x velocity
 Mass is measured in kilograms (kg).
 Velocity is measured in metres per second (m/s).
 Momentum is measured in kilogram metres per
second (kg m/s).
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Scalar or vector?
Velocity is a vector quantity – this means it has a magnitude
(size) and direction.
Scalar quantities, such as speed, only have a magnitude.
As velocity is needed to calculate momentum, momentum
must also be a vector quantity and it therefore has a direction.
If two objects of the same mass are moving in opposite
directions but at the same speed (i.e. their velocities are
different), the momentum of each object will be of the
same magnitude but a different direction.
A ‘+’ and a ‘-’ are often used to indicate the direction of
momentum of moving objects.
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Calculating momentum question
An aircraft carrier has a
mass of 1,000,000 kg
and a velocity of 15 m/s.
What is its momentum?
momentum = mass x velocity
= 1,000,000 x 15
= 15,000,000 kg m/s
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Tasks – You must manage the time allotted to you in order to
complete the following tasks in whichever order you want:
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•
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1) Copy and complete:
Momentum is a measure of how ……….. it is to stop a moving
object.
The more ………. an object has the more momentum it can have.
The bigger the ………… of an object, the more momentum it can
have.
…………… (kgm/s) = Mass (kg) x Velocity (m/s)
velocity
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•
•
•
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mass
difficult
momentum
2) Calculate the momentum of:
a) An athlete of mass 60 kg running at a velocity of 10 m/s.
b) A car of mass 800 kg travelling at a velocity of 30 m/s.
c) A ship of mass 20 million kg travelling at a velocity of 5 m/s.
d) A plane of mass 80 000 kg travelling at a velocity of 300 m/s.
3) Complete the sheet from your teacher
4) Describe what a scalar and a vector are and describe which
momentum is.
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PLTS: Self-managers – organise
own time.
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Name……………...
Complete the momentum table below:
momentum
mass
velocity
kg m/s
50 kg
3 m/s
160 kg m/s
kg
20 m/s
1500 kg m/s
250 kg
m/s
kg m/s
500 g
8 m/s
3 kg m/s
kgkg
50 cm/s
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Complete
Answers
momentum
mass
velocity
150 kg m/s
50 kg
3 m/s
160 kg m/s
8 kg
20 m/s
1500 kg m/s
250 kg
6 m/s
4 kg m/s
500 g
8 m/s
3 kg m/s
6 kgkg
50 cm/s
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Momentum calculations - Plenary
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