# Physics PRINTED

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What is the formula for kinetic energy?
Kinetic energy=1/2 * Mass (Kg) * Speed^2 (m/s^2)
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What does the momentum of an object depend on?
Its mass and velocity.
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How is momentum a vector quantity?
It has both size (magnitude) and direction.
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When does an object have more momentum?
When there is a greater mass and the greater its velocity.
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What is the formula for momentum?
Momentum (kg m/s) = Mass(Kg) * Velocity (m/s)
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What happens to momentum of an object when a force acts on a moveable object?
It changes the object's momentum
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How do you work out the force that acts upon an object?
Force (N)=Change In Momentum (kg m/s)/ Time that the force acts (s)
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What happens when 2 objects collide?
They exert force on each other. The momentum of one of them increases; and the other decreases.
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What is the rule about momentum?
THE TOTAL MOMENTUM STAYS THE SAME. We say that momentum is conserved which means that the total momentum before a collision=total momentum after a collision
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Why do cars have crumple zones?
They are parts of the car that fold up in a crash. This means that the collision time is longer; so the impact force is less.
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In any collision; to change your momentum a force is exerted on you for a length of time. What is the rule for this?
The longer the time; the smaller the force.
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Why do cars have air bags?
They inflate very quickly during a collision. Because of the air bags; the change in momentum of the driver is spread out over a longer period of time; so the force is less
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Why do cars have seatbelts?
They stretch in a collision; to make the deceleration time longer.
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Why is a steering wheel/cyclists helmet usually padded?
If you hit it; it spreads out the collision over a longer time.
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Why do you bend your knees when you jump down?
To spread out the collision time.
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What do electrons flow through?
A solid conductor e.g. a copper wire. Electrons flow easily through metals; which are good conductors because they have free electrons.
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What is the rate of flow of electric charge called?
The current
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What is the formula for current?
Current (Amps)= Charge (Coulombs/C) /Time (s)
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What is the danger of electrostatics?
The more change you put on an object; the higher the voltage (potential difference) between the object and earth. If the potential difference is very high, a spark can jump between the object and any earthed conductor.
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Why are aeroplanes and tankers connected by a copper wire when refuelling?
A liquid (or powder) flowing through a pipe can become charged by rubbing. This can be dangerous if it causes a spark and the substance is inflamable. Using a copper wire gets rid of the sparks/static before it goes into the aeroplane.
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What is an electrostatic precipitator? What does it do?
Can be used to remove smoke particles in chimney. Smoke particles pick up the positive charge as they go through grid; then repelled by positive grid and attracted to (negative) plates. Particles stick there; until knocked off + collected.
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What happens in a photocopier? (Static)
Metal drum is charged up. Image of page projected on drum. Where light shines on drum charges leak away; leaves pattern on page. Black ink powder attracted to charged parts of drum. Ink transferred to paper. Paper heated so ink powder melts + sticks.
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Open Switch? Closed? Cell? Battery? Diode? Resistor? Variable Resistor? Fuse? Thermistor? LDR? Lamp? Ammeter? Voltmeter?
Look In Physics for You book; page 66.
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What is the current like in a series circuit? Voltage?
The current is the same the whole way round. The voltage is shared through all the resistors.
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What is the current like in a parallel circuit? Voltage?
The current is shared between the branches. The voltage is the same the whole way round.
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## Other cards in this set

### Card 2

#### Front

What does the momentum of an object depend on?

#### Back

Its mass and velocity.

### Card 3

#### Front

How is momentum a vector quantity?

### Card 4

#### Front

When does an object have more momentum?

### Card 5

#### Front

What is the formula for momentum?