Yr 8 Energy Revision

Yr 8 Energy Revision

By Terena Holdaway-Clarke

​What is energy? How is it measured?

Energy is the capacity to "make something happen"

such as moving something or making a light glow.

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​Energy is measured in Joules - the symbol is J

Multiple Choice

Energy is

• A force

• The capacity to make something happen

• how fast something goes

• how fast the particles are moving

Multiple Choice

What is the unit for energy?

• Joules (J)

• degrees Celcius

• Newtons (N)

Types of potential energy

Gravitational

Elastic

Chemical

Nuclear (stored in the nucleus of atoms)

Electrical (such as is available in batteries or electrical outlets)​

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Other types of energy

Kinetic (energy of moving objects)

Heat energy (moving particles)​

Sound energy (moving particles in the air)

Light energy (carrie​d by electromagnetic waves)

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Multiple Choice

Type of energy posessed by a stretched spring

• Kinetic

• gravitational potential

• Elastic potential

• Electrical

Multiple Choice

Type of energy possessed by a book on a shelf

• gravitational potential

• kinetic

• electric

• sound

Kinetic energy can be calulated

KE = 1/2 m v²

Where m = mass

v = speed​

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Gravitational potential energy can be calculated:

​GPE = mass x acceleration due to gravity x height

​ = m g h

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Acceleration due to gravity on Earth = 10* m/s²​

​Actual acceleration due to gravity is 9.8 m/s²

Multiple Choice

Using g = 10 m/s², the gravitational potential energy of a 5 kg mass 0.5 m off the ground is

• 5 J

• 10 J

• 25 J

• 50 J

Multiple Choice

The kinetic energy of a 200 kg car travelling at 5 m/s

• 2500 J

• 5000 J

• 200 J

• 10000 j

Conservation of energy

Energy cannot be created or destroyed, only transformed or transferrec

Energy is transformed when it changes from one form to another​

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Heat is a form of energy

Temperature is NOT HEAT it is how hot or cold something is and an indication of the average speed of the particles in an object - it is measured in degrees Celcius

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​Heat is measured in Joules and is the amount of thermal energy an object has

Multiple Choice

Identify the energy transformation when a runner eats before a race

• kinetic to chemical

• nuclear to sound

• chemical to kinetic

• heat to light

Multiple Choice

What unit is used for heat?

• Joules

• degrees Celcius

Multiple Choice

In a mobile phone, an example of wasted energy is

• sound

• light

• kinetic

• heat

Heat can be transferred by

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​Conduction - hot (fast) particles bump cooler (slower) particles.

Energy transferred hot to cold

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Convection - bulk movement of hot liquid or gas upward as it is less dense

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Radiation - given off by hot objects​

Multiple Choice

This is an example of

• Conduction

• Convection

• Radiation

Multiple Choice

Electricity will only flow in

• an open circuit

• a complete battery

• a closed circuit

• a short circuit