SP8a - What is work done?

The energy transferred by a force as it moves an object in the direction of a force.

SP8a - What is the equation for work done?

E = F x d

(Energy = Force x distance moved)

SP8a - What is the equation for Power?

P = E ÷ t

(Power = Energy ÷ time)

SP8a - What is the unit for power?

W - Watts

(Equivalent to J/s - Joules per second)

SP9a - What do you call forces between objects that are touching?

Contact forces

SP9a - What is the name for the regular upward force form the ground when you're standing?

Normal contact force

SP9a - What are the three non-contact forces?

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- Gravitational fields
- Static electricity
- Magnetism

SP9a - What do all objects that produce a non-contact forces have?

A force field.

An area around an object in which another object could experience a force.

SP9a - Describe how the gravitational pull between the earth and the moon are action-reaction forces.

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- Force is a vector quantity.
- The force of the moon on the earth is the same size as the earth on the moon but they are in opposite directions.
- Neither objects move in the direction of the force.

SP9c - What is the formula for a moment?

Moment (N m)

=

Force (N) x distance perpendicular to the pivot (m)

SP9c - What could you say when weights around a pivot are balanced?

It is in equilibrium

SP9c - What is the principle of moments?

The some of clockwise moments = the sum of anti-clockwise moments

[When a system is in equilibrium]

SP9b - How do you work out the direction and size of the resultant force using the component forces?

The Parallelogram method:

- (If the start of a diagram hasn't already been provided, draw to the two forces using a scale)
- Draw another pair of dashed-lines parallel to the forces
- This should form a parallelogram
- Draw a line from the object to the vertically opposite corner
- Measure this line and use the scale to work out the size
- If required, measure the angle to show the direction

SP9b - How do you resolve the component forces using the resultant force?

The Rectangle method:

- Draw faint horizontal and vertical lines fom the object
- Measure the angle from the horizontal/vertical that the object is at
- Using a scale, draw a line the represent this force
- Draw lines down and across from where this line ends to the horizontal and vertical respectively
- Measure out the length from the object to each of these poitns
- Use the scale to work out the size

SP9c - Explain why using two different sized gears in a car may be beneficial.

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- The first smaller gear can be connected to the motor where it recieves the moment
- This passes on an equal force to the second larger gear
- Since the second gear is larger, it will have a larger radius.
- This means that its the distance from the pivot will be greate
- Therefore it will have a larger moment (turnign force) as M = F x d

SP9c - Why is a longer lever more effective?

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- The formula for a moment (the turning force) is M = F x d
- Thus, by increasing the distance form the pivot, you will either:

- Increase the turning force
- Decrease the force required to produce the same turning force

SP10a - Describe the structure of an atom including features of the sub-atomic particles.

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- Proton and neutron in the nucelus, each with a relative mass of 1.
- Protons have a charge of +1.
- Electrons orbit in energy levels each with a charge of -1 and a relative mass of 1/1835 (negligible)

SP10a - Descirbe what a potential difference is.

The force that pushes the electrons to flow around the circuit.

SP10a - What is conventional current?

What we refer to as the direciton of current from positive to negative. Opposite to the flow of electrons.

SP10a - What are the two types of circuits?

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- Series: everything connected in one route
- Parallel: many options for different routes.

SP10a - Why may parallel circuits be more beneficial?

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- If the circuit becomes incomplete along one path, the rest of the circuit can still continue to function. (e.g - Switches can be connected to different parts meaning lights in parallel to each other can be switched in and off individually)
- If a bulb goes off, the rest of the circuit in parallel to this can still continue to function

SP10b - What is the unit for current and how can it be measured?

Amps (Amperes). Measured using an ammeter which is attached in series to the circuit

SP10b - What is the unit for potential difference and how can it be measured?

Volts. Measured using a voltmeter which is attached in parallel to the component you are measuring the potential difference of.

SP10b - How does total current differ in parallel and series circuits?

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- S: The total current is the same at all points throughout the circuit
- P: The total current gets split between the branches of the circuit, inversely proportionate to the resistance of the components in those branches.

SP10b - How does potential difference differ in parallel and series circuits?

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- S: The p.d is different across different components, directly proportionate to the resistance of that component
- P: The p.d is tha same at all points across the circuit

SP10c - What is current?

###
- The flow of electrons
- The rate of flow of charge

SP10c - What is the unit for charge?

C - Coulombs

SP10c - What is the equation linking charge and current?

Q = I x t

(Charge = Current x time)

SP10c - What equation links energy and charge and how can this be changed to link energy to current?

**E = Q x V** (Energy = Charge x p.d)

since **Q = I x t**, this means that

**E = I x t x V** (Energy = Current x time x p.d)

SP10d - What is Ohm's law?

V = I x R

(p.d (V) = Current (A) x Resistance (Ω))