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Common q Flashcards

pair with defintions and chapters + ultrasound + electromagnetic forces + electromagnetic induction

1
Q

As the trolley moves across the rough surface, it slows down and stops. Explain, in
terms of the work done, the energy change that takes place as the trolley slows down.

A

work done due to friction or kinetic energy (of trolley) used to do work

kinetic energy transfers to thermal energy

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2
Q

Why a bus begins to topple?

A

their centres of mass
would be to the right of the ‘pivot’ (the
right-hand wheel) which would exert a
clockwise moment.

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3
Q

State the principle of the conservation of momentum.

A

the total momentum is constant and does not change because of an interaction between bodies such as collisions

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4
Q

State the principle of conservation of energy.

A

energy cannot be created or destroyed; it can only be stored or transferred

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5
Q

State two properties of an object that may be changed by the action of forces.

A

size, shape (direction of motion, velocity)

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6
Q

State the two conditions which must be true for an object to be in equilibrium.

A

no resultant force, no resultant moment

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7
Q

Hooke’s law

A

the extension of an object is proportional to the load producing it

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8
Q

Explain what is meant by the term limit of proportionality of the spring.

A

up to this limit, Hooke’s law s obeyed (so extension is proportional to load)

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9
Q

What type of energy is stored in springs?

A

elastic potential energy.

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10
Q

Describe and explain the motion of an object released from top of an fluid, from
when it is released until it reaches terminal velocity.

A

Initial acceleration caused by weight.
Air resistance increases with speed of motion.
Acceleration decreases as air resistance increase.
When weight= air resistance there is no resultant force. He falls at constant speed at terminal velocity.

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11
Q

Explain why opening the parachute cannot reduce the speed of the skydiver to zero.

A

Open parachute causes air resistance. At zero speed, there is no air resistance. Weight is acting downwards. Forces can only balance at a speed greater than zero, so no decrease in speed.

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12
Q

Why not 100% of GPE is converted to KE when an object falls?

A

(work done against) friction or thermal energy generated

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13
Q

Describe the motion of molecules of the gas.

A

move freely and randomly, collide into each other and walls, high speed which increases with temp

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14
Q

Describe the motion of molecules of the solid.

A

tightly packed, so cannot move around (so vibrate in fixed positions, the hotter, the more they vibrate)

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15
Q

State two ways in which the molecular structure of liquid is different from the
molecular structure of solid.

A

less tightly packed close together, arranged randomly and not in a fixed position

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16
Q

Describe, in terms of molecules and their motion, how a liquid differs from a gas.

A

molecules close(r)
molecules do not move freely
molecules vibrate and move

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17
Q

Why solids have fixed shapes? Explain in terms of forces between molecules and
arrangement of molecules.

A

regular lattice arrangement, particles are packed tightly together, strong forces between molecules

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18
Q

Why liquids adapt to the shape of their container? Explain in terms of forces
between molecules and arrangement of molecules.

A

particles are free to move within liquid, no fixed shape, irregular lattice arrangement, forces weak

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19
Q

Why gas fills their container? Explain in terms of forces between molecules and
arrangement of molecules.

A

particles are free to move, weak forces, far apart

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20
Q

Explain the melting of a solid in terms of molecules and energy.

A

energy is required to break bonds, solid expands and particles are slightly further apart

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21
Q

The gas bubble rises to the surface. The volume of the gas bubble increases as it
rises higher in the water. Explain why the volume of the bubble increases.

A

pressure decreases with depth, pressure is inversely proportional to volume

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22
Q

Explain, in terms of particles, why it is difficult to compress liquids.

A

particles are close together, forces between particles are large

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23
Q

Sound waves are diffracted through doorways. Light waves from a television are not diffracted through doorways. Suggest why light waves and sound waves behave differently in this situation.

A

Wavelength of light is smaller than wavelength of sound. Small gaps are needed to see light being diffracted. The greater the wavelength of waves the greater the angle they are diffracted.

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24
Q

Define compression and rarefaction.

A

compression: region of sound wave where particles are pushed together, so the region is dense
rarefaction: region of sound wave where particles are further apart, so the region is less dense

(longitudinal: rarefactions and compressions, transverse: crests and troughs)

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25
Q

What are:
seismic waves
P-waves
S-waves

A

seismic: waves caused by earthquakes
P-waves: fast-moving, longitudinal seismic waves
S-waves: slow-moving, transverse seismic wave-

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26
Q

The greater the amplitude of a sound..

A

the louder the sound

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27
Q

Frequencies that humans can hear?

A

20-20000Hz

28
Q

Sounds are caused by..

A

vibrating sources

29
Q

The sound wave passes from the sea-water into the air. What happens to the frequency, wavelength and speed?

A

speed decreases, frequency remains the same, wavelength decreases

30
Q

Loudness is increased, what happens to the amplitude and wavelength?

A

Wavelength stays the same, amplitude increases.

31
Q

Pitch is increased, what happens to the amplitude and wavelength?

A

Amplitude stays the same, wavelength decreases.

32
Q

High frequency means..
High amplitude means..

A

high pitch
loud sound

33
Q

Define wavelength.

A

the distance between two adjacent crests (or troughs)

34
Q

Define frequency.

A

the number of complete vibrations or waves per unit time

35
Q

How does a wavelength look?

A

Two big loops, 4 halves

36
Q

Where are the crest and trough located?

A

Crest is top point, trough is bottom point

37
Q

Reflection definition

A

the change in the direction of a ray when it strikes a surface without passing through it (can also occur in waves)

38
Q

Define refraction

A

the bending of light when it passes from one medium to another (can also occur in waves)

{rays are closer to the normal, slow at the shallow, ‘light rays’ at right angles to ripples, submerged glass plate for depth}

39
Q

Define diffraction

A

when a wave spreads out as it travels through a gap or past the edge of an object

40
Q

Refractive index formulas

A

n=sini/sinr
n=1/sinc
n=speed of light in air/speed of light in oil

41
Q

What are the uses of radio waves?

A

broadcast radio and television signals, radio astronomy, radio frequency identification (RFID), Bluetooth, wifi

42
Q

What are the uses of microwaves?

A

microwave ovens, satellite television broadcasting, transmit mobile phone signals

43
Q

What are the uses of infrared radiation?

A

remote controls in devices such as televisions, grills and toasters, security alarms, optical fibres, medicine: detect heat which may indicate infection or to speed up healing and reduce pain

44
Q

What are the uses of visible light?

A

to see, optical instruments such as cameras, telescopes and microscopes, photosynthesis

45
Q

What are the uses of ultraviolet light?

A

forensic scientists find evidence at crime scenes not visible to the eye, security marking of valuable equipment and banknotes, sterilise water

46
Q

What are the uses of x-rays?

A

security scanners at airports, see inside patients without surgery (bones absorb x-rays so it will appear as a shadow (shadowgraph))

47
Q

What are the uses of gamma rays?

A

damage or kill living cells (such as cancerous cells), sterilise surgical instruments, detection of cancer

48
Q

Describe the advantages of using ultrasound waves instead of x-rays.

A

not dangerous= cannot harm the tissues, DNA damaged= genes may be passed on and mutation can occur in the offspring which is often harmful

49
Q

Explain, in terms of wave theory, what occurs as the wavefront strikes the boundary.

A

i=r, moves at same speed

50
Q

To calculate how many kilometres away is a storm,

A

measure the time between, and divide by 3

51
Q

Describe how the movement of the loudspeaker cone produces these regions of different
pressure.

A

Cone moves forward and pushes air particles together. Cone moves backwards which allows for more space between air particles.

52
Q

The man with his ear to the railway line actually hears two sounds from the hammer,
separated by a short interval.
Explain why he hears two sounds.

A

sound through air and sound through steel

speeds in air and steel are different

53
Q

Define electromagnet.

A

a coil of wire that acts as a magnet when an electric current passes through it

54
Q

Define solenoid

A

an electromagnet made by passing a current through a coil of wire

55
Q

How can you increase the strength of an electromagnet? How can the field be reversed?

A

greater current, number of turns, add soft iron core

reversing the direction of the current

56
Q

Magnetism rules

A

Magnetic materials can be magnetised. Becomes a magnet when magnetised. Non-magnetic materials cannot be magnetised

57
Q

The north pole is brought close to the pin, what pole is induced?

A

south, so they attract

pin will return to unmagnetised state or may retain a small amount of magnetism

58
Q

draw an eye suitably placed to view the image I.

A

wide part of defined light rays, to the right of lens

59
Q

Describe one example of how optical fibres are used in medicine.

A

Light travels down in the optical fibres and back upwards in an endoscopy, which allows the doctor to see so they can examine or do surgery on an organ.

60
Q

A wave enters glass, what happens to its speed and wavelength?

A

speed decreases, wavelength decreases

61
Q

As light enters glass, what happens to its frequency and wavelength?

A

wavelength decreases, frequency stays the same

62
Q

State an application in which a convex lens is used in this way. Image is magnified.

A

magnifying glass

63
Q

State the term which describes the separation of red and violet refracted rays in glass.

A

dispersion of light

64
Q

Explain, in terms of molecules, why a liquid expands when heated.

A

molecules gain kinetic energy and move faster
molecules push others away and move further apart

65
Q

Why does thermal expansion happen?

A

Particles gain thermal energy and move faster, pushing each other further apart.

66
Q

Explain, in terms of forces between molecules, why gases expand more than liquids when they have the same rise in temperature. Assume that the pressure remains constant.

A

Forces weaker. Less work done to separate molecules for the same increase in energy. Great distance between them.

It is difficult for solid particles to push their neighbours aside, so it does not expand that much.

+ expansion

(Particles do not get any bigger)

67
Q

Expansion of a gas.

A

Particles gain energy, move faster and push with greater force. Particles are further apart.

PT (14 decks)

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