Revision

ForcesWhat is the motion of this box?

What is the Resultant Force?

500N

300N30

0N

150N

ForcesWhat is the motion of this box? Accelerating

What is the Resultant Force? 350N

500N

300N30

0N

150N

Forces – Key Points

• Forces act in pairs. • Balanced forces result in NO change in motion

(i.e. remain stationary or at a constant speed).• Unbalanced forces result in acceleration or

deceleration.• The resultant force is the overall force acting on a

object (i.e. forward forces – backward forces). • As speed increases, drag increases until the

forward force equal backward forces.

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• Jan 2011 – Question 1

Static Electricity

• What is static electricity?• How does a material become charged?• What is an ion?• What is earthing?

Static Electricity

• What is static electricity? Electrons moving• How does a material become charged?

Materials rubbing together (friction)• What is an ion? Where an electron is lost OR

gained. • What is Earthing? Where the current is given

an alternative (safer) and quicker route to the earth.

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• Jan 2011 – Question 2

Radiation

• What causes background radiation?• How do elements differ from each other?

Radiation

• What causes background radiation? Rocks, food, cosmic rays, x-rays, nuclear power stations, nuclear weapons testing,

• How do elements differ from each other? They have a different number of protons (atomic number).

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• Jan 2011 – Question 3

• Also try – Question 4 (apply what is given in the question).

Electricity

• Give the names of some electrical components.

• Which component allows electricity to flow in one direction only?

• What is the difference between the position of an ammeter and voltmeter in a circuit?

• How does current vary in a series circuit?

Electricity

• Give the names of some electrical components. Bulb, diode, resistor, cell, LDR, Thermistor

• Which component allows electricity to flow in one direction only? Diode

• What is the difference between the position of an ammeter and voltmeter in a circuit? Ammeter goes in series, voltmeter is placed in parallel to the component being tested (across the device)

• How does current vary in a series circuit? Same at all positions.

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• Jan 2011 – Question 5 & 6

Momentum

• What are the units of Momentum?• What is the equation for Momentum?• What is the equation that links force,

acceleration and mass?• How does an airbag reduce injury?

Momentum

• What are the units of Momentum? Kg m/s• What is the equation for Momentum?

Momentum = mass x velocity • What is the equation that links force, acceleration and

mass?Force = mass x acceleration

• How does an airbag reduce injury?- Increases the time taken for the head to stop- Decreases the rate of change in momentum - Reduced the force on the head.

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• Jan 2011 – Question 7