Physics Flashcards

1
Q

What is terminal velocity

A

when the weight of the object falling and the air resistance is the same, therefore leaving us with no resultant force

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2
Q

What is the SI unit of density

A

kg/m³

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3
Q

What does density equal to

A

Density = mass/volume

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4
Q

what is hooke’s law

A

a law stating that the strain in a solid is proportional to the applied stress within the elastic limit of that solid.

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5
Q

What is the weight of a body of mass 1kg

A

the weight of a body of mass 1kg is 9.8N (often taken as 10N)

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6
Q

What is the weight of a body

A

The weight of a body is the force of gravity on it

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7
Q

Weight equation

A

weight equals mass X gravitational field strength

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8
Q

How to determine resultant force on a suspended weight

A

Amount of Newtons (on cable) x sine(angle the cable makes with horizon)

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9
Q

What does moment equal to

A

Force X distance

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10
Q

How long can an object stay upright

A

until the centre of mass is outside the base

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11
Q

the greater the distance from the hinge… (moment)

A

The less force required to move an object

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12
Q

What is work

A

Work is force x distance moved in direction of force

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13
Q

what are the two quantities to measure to calculate the useful work done when a load is lifted from the ground to a higher level

A

Weight and height

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14
Q

Why is the force required to lift a load higher when it is just leaving the floor

A

there is a force needed to get it started

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15
Q

What is the unit of work

A

Joules, the work done when 1 newton moves through 1 meter

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16
Q

What is the Kinetic energy equation

A

which is 0.5mv^2

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17
Q

Name three different emerge resources used to obtain energy directly from water

A

hydroelectric
tidal
wave

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18
Q

How does wave energy convert to electrical energy

A

Wave power converts the periodic up-and-down movement of the oceans waves into electricity by placing equipment on the surface of the oceans that captures the energy produced by the wave movement and converts this mechanical energy into electrical power.

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19
Q

what is gas pressure equal to

A

Atmospheric pressure + pressure due to liquid column

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20
Q

resistance equation

A

Voltage(V)/resistance(A)

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21
Q

How many Amps is one mA

A

1000

22
Q

What measures current

A

Ammeter

23
Q

what measures volts (pd)

A

Voltmeter

24
Q

how to calculate current

A

Current = voltage/resistance

25
Q

voltage equation

A

Current x resistance

26
Q

how do variable resistors work

A

A variable resistor works by adjusting the path that current has to flow. … The dial you turn will move another piece of wire inside the resistor. The end result is that the electricity will travel through a certain length of the strip depending on where you turn the knob.

27
Q

what are the two types of resistor setups

A

Parallel, series

28
Q

How to calculate combined resistance in parallel

A
1/R1 = 1/R1 + 1/R2 etc… 
1/R1 = 3/R2 
R1/1 = R2/3
29
Q

When is a current induced in the wire (u shaped magnet)

A

A current is induced in the wire when it is moved up or down between the magnet poles

30
Q

What does the voltage increase with

A

the speed of motion of the magnet or coil
The number of turns on the coil
the strength of the magnet

31
Q

What is Faraday’s law

A

The size of the induced p.d. is directly proportional to the rate at which the conductor cuts magnetic field lines

32
Q

what is Lenz’s law

A

The direction of the induced current is such as to oppose the change causing it

33
Q

Right hand rule

A

thuMb: Motion
First finger: Field
seCond finger: induced Curret

34
Q

How does a simple a.c. generator (alternator) work

A

It consists of a rectangular coil between the poles of a C shaped magnet
The ends of the coil are joined to two split rings on the axle and against which carbon brushes press. When the coil is rotated it cuts the field lines and a voltage is induced in it

35
Q

How does a simple d.c. generator (alternator) work

A

An a.c. generator becomes a direct current if the slip rings are replaced by a commutator like that in a d.c. motor
The brushes are arranged so that as the coil goes through the vertical, changeover of contact occurs from on half of the split ring of the communicator to the other. But it is when the coil goes through the vertical position that the voltage induced in the coil reverses, so one brush is always positive and the other negative

36
Q

transformer equation

A

Secondary voltage/primary voltage = secondary turns/primary turns

37
Q

How is voltage increased/decreased across transmission lines

A

Step up/ step down transformers

38
Q

What is the purpose of the iron core

A

Magnetic linkage

39
Q

List five devices that make use of electromagnetic induction

A

transformer, generator, dynamo, microphone, alternator

40
Q

What is meant by electromagnetic induction

A

Magnetic field cut by conductor induces a current

41
Q

how to increase the magnitude of the induced emf in this experiment

A

Move magnet faster, stronger magnet, more turns of solenoid

42
Q

how to calculate mass of water

A

Mass = volume × density

43
Q

How to calculate work

A

Work = Force × Distance

44
Q

How to calculate density of liquid

A

divide mass by volume

45
Q

what increases the sensitivity of a thermometer

A

A capillary tube with a very small diameter

46
Q

define virtual image

A

an optical image formed from the apparent divergence of light rays from a point, as opposed to an image formed from their actual divergence.

47
Q

How is a virtual image made

A

Virtual images form when light rays from the same location on an object reflect off a mirror and diverge or spread apart. Real images form when light rays from the same location on an object reflect off a mirror and converge or come together.

48
Q

A student wants to demagnetise a steel bar. He switches on the circuit for a few seconds and then switches off. He finds that the steel bar is still magnetised.
How should he improve his method

A

Remove the steel bar from the coil whilst the circuit is switched on

49
Q

REMINDER

A

Study logic gates and circuits, can’t do flash cards for it

50
Q

A beam of electrons is passed through the magnetic field of a magnet, how must the magnet be positioned to deflect the beam in the direction shown

A

Have the magnet on its side, with S on the top and N on the bottom, when the electrons go through it will be redirected