Weightlessness
1 card- 01
Astronauts on the International Space Station float. Why?
- A
There is no gravity in space
- B
Their spacesuits cancel their weight
- C
The station is far enough away that Earth's gravity is negligible
- D
The station and everything in it are in free fall around the Earth; gravity there is still about 90% of its surface value
- A
Free fall
2 cards- 02
A bowling ball and a tennis ball are dropped together from the same height in a vacuum. Which lands first?
- A
The tennis ball: it has less inertia to overcome
- B
The bowling ball, but only by a fraction of a second
- C
They land together: without air, everything falls with the same acceleration
- D
The bowling ball: gravity pulls harder on heavier objects
- A
- 03
A stone is dropped from a bridge and hits the water after 3 s. Ignoring air resistance and taking $g = 9.8$ m/s², how high is the bridge?
- A
About 29 m
- B
About 44 m
- C
About 88 m
- D
About 15 m
- A
Newton's laws of motion
2 cards- 04
A book lies still on a table. Which is the reaction force, in Newton's third-law sense, to the Earth's gravitational pull on the book?
- A
The book's gravitational pull on the Earth
- B
The book pushing down on the table
- C
The table pushing up on the book
- D
There is none: the book is not moving
- A
- 05
A car travels along a straight road at a steady 100 km/h. What is the net force on it?
- A
Zero: the engine's push exactly balances drag and friction
- B
Forward, equal to the engine force
- C
Forward, because it is moving forward
- D
Backward, because drag acts on it
- A
Centrifugal force
1 card- 06
You are in a car turning sharply left, and you feel thrown against the right-hand door. What is actually happening?
- A
Your body tries to continue in a straight line; the door pushes you left to make you turn with the car
- B
A centrifugal force pushes you outwards
- C
Gravity shifts towards the outside of the bend
- D
The car's turning creates a force field pointing right
- A
Momentum
1 card- 07
A 1,000 kg car at 20 m/s and a 2,000 kg truck at 10 m/s have the same momentum. Which has more kinetic energy?
- A
The truck: it is heavier
- B
They are equal, since momentum is equal
- C
It cannot be decided without knowing the direction
- D
The car: kinetic energy depends on the square of the speed
- A
Braking distance
1 card- 08
A car's braking distance from 30 km/h is 5 m. Roughly what is it from 60 km/h, on the same road?
- A
About 20 m
- B
About 10 m
- C
About 7 m
- D
About 40 m
- A
Terminal velocity
1 card- 09
A skydiver falls for a while and reaches a steady speed before opening the parachute. Why does the speed stop increasing?
- A
The skydiver runs out of energy
- B
Air becomes denser lower down and holds the skydiver up
- C
Air resistance grows with speed until it equals the skydiver's weight, and then the net force is zero
- D
Gravity weakens as the skydiver falls
- A
Tide
1 card- 10
Why are there two high tides a day, not one?
- A
The Moon's pull is stronger on the near side of Earth than on the far side, stretching the oceans into two bulges
- B
The Moon orbits Earth twice a day
- C
The Sun causes the second one
- D
The Earth's rotation flings water outward on the far side
- A
Season
1 card- 11
Why is it summer in the northern hemisphere in July?
- A
Earth is closest to the Sun in July
- B
Earth's axis tilts the northern hemisphere towards the Sun, giving longer days and more direct sunlight
- C
The Sun is hotter in July
- D
The northern hemisphere is nearer the Sun than the southern
- A
Lift (force)
1 card- 12
The common textbook explanation says an aircraft wing lifts because air over the curved top must travel further and so faster, lowering the pressure. What is wrong with it?
- A
The pressure above a wing is higher, not lower
- B
Nothing forces air over the top to reunite with air underneath; the top air actually arrives much earlier, and flat or inverted wings fly too
- C
Air over the top is slower, not faster
- D
Nothing: it is the complete explanation
- A
Thermal conductivity
1 card- 13
In the same room, a metal chair feels colder than a wooden one. Why?
- A
Metal conducts heat away from your hand much faster; both chairs are at the same temperature
- B
Wood generates a little heat as it slowly decays
- C
Metal is always colder than wood
- D
Metal stores less heat, so it is colder
- A
Glass
1 card- 14
Old church windows are thicker at the bottom. Is this because glass is a very slow-flowing liquid?
- A
No: glass is an amorphous solid and does not flow at room temperature; the panes were made uneven and usually installed thick side down
- B
No: the glass has been eroded at the top by rain
- C
Yes: glass is a supercooled liquid and always sags
- D
Yes: glass flows visibly over centuries
- A
Microwave oven
1 card- 15
Does a microwave oven cook food from the inside out?
- A
Yes: water in the centre absorbs the most energy
- B
No: microwaves penetrate only a centimetre or two and heat the outer layer; the interior heats by conduction from there
- C
No: it heats only the surface, like a grill
- D
Yes: microwaves pass through the surface and heat the centre first
- A
Mirror
1 card- 16
A mirror seems to swap left and right but not top and bottom. What does it really do?
- A
It swaps left and right because our eyes are side by side
- B
It rotates the image by 180° around the vertical axis
- C
It reverses front and back; the left–right description comes from us imagining ourselves turned around to face the image
- D
Nothing is swapped; the image is identical to the object
- A
Speed of sound
1 card- 17
You see a lightning flash and hear the thunder 6 seconds later. Roughly how far away was the strike?
- A
About 200 m
- B
About 2 km
- C
About 20 km
- D
About 6 km
- A
Doppler effect
1 card- 18
An ambulance siren sounds higher-pitched as it approaches and lower as it moves away. Does the siren's frequency change?
- A
No: the change is in loudness, which the ear hears as pitch
- B
Yes: the siren is driven harder when the vehicle accelerates
- C
No: the siren emits the same frequency; motion compresses the waves reaching you as it approaches and stretches them as it recedes
- D
Yes: the speed of sound changes with the vehicle's speed
- A
Diffuse sky radiation
1 card- 19
Why is the sky blue?
- A
Blue light is the most abundant in sunlight
- B
Air molecules scatter short (blue) wavelengths of sunlight much more strongly than long (red) ones, so blue light reaches us from every direction
- C
The atmosphere is faintly blue in colour, like a thick sheet of glass
- D
The sky reflects the colour of the oceans
- A
Refraction
1 card- 20
A straw in a glass of water looks bent at the surface. Why?
- A
The glass acts as a lens
- B
Water absorbs some colours and distorts the image
- C
Light from the submerged part bends as it leaves the water, so your eye traces it back to a shifted position
- D
Water pressure bends the straw slightly
- A
Thermal expansion
1 card- 21
A metal ring is heated. What happens to the hole in the middle?
- A
It depends on the metal
- B
It gets larger: every dimension of the metal expands, including the gap
- C
It gets smaller: the metal expands inward into the hole
- D
It stays the same: only the metal changes
- A
Equations of motion
1 card- 22
A car accelerates uniformly from rest to 20 m/s in 8 s. What is its acceleration, and how far does it travel?
- A
2.5 m/s², 160 m
- B
2.5 m/s², 80 m
- C
160 m/s², 20 m
- D
0.4 m/s², 80 m
- A
Weight
1 card- 23
A 60 kg person stands on bathroom scales in a lift. The lift accelerates upward at 2 m/s². What do the scales read? (Take $g = 10$ m/s².)
- A
480 N (48 kg)
- B
600 N (60 kg)
- C
720 N (equivalent to 72 kg)
- D
120 N (12 kg)
- A
Hooke's law
1 card- 24
A spring stretches 4 cm when a 2 N weight hangs from it. How far will it stretch with 5 N, assuming it stays within its elastic limit?
- A
2.5 cm
- B
10 cm
- C
20 cm
- D
7 cm
- A
Pressure
1 card- 25
Why can a person lie on a bed of nails unharmed, when standing on a single nail would drive it into the foot?
- A
The weight is spread over hundreds of nails, so the pressure on each point of skin is far below what breaks it
- B
Lying down reduces a person's weight
- C
The nails on a bed are blunter
- D
Muscles tense and harden the skin when lying flat
- A
Buoyancy
1 card- 26
A steel ship floats, but a steel ball sinks. Why?
- A
Salt water is dense enough to support steel
- B
Ships are made of a lighter kind of steel
- C
The ship's hull encloses a large volume of air, so its average density is less than water's and it displaces its own weight before submerging
- D
The ship's engines push it upward
- A
Density
1 card- 27
A block of aluminium (density 2,700 kg/m³) measures 10 cm × 5 cm × 2 cm. What is its mass?
- A
270 g
- B
27 g
- C
2.7 kg
- D
100 g
- A
Kinetic energy
1 card- 28
A 2 kg ball is thrown at 3 m/s. What is its kinetic energy?
- A
6 J
- B
3 J
- C
9 J
- D
18 J
- A
Potential energy
1 card- 29
A 0.5 kg ball is dropped from 5 m. Ignoring air resistance and taking $g = 10$ m/s², how fast is it moving when it hits the ground?
- A
50 m/s
- B
10 m/s
- C
5 m/s
- D
25 m/s
- A
Power (physics)
1 card- 30
A 60 kg student climbs a 4 m flight of stairs in 8 s. What is their average power output? (Take $g = 10$ m/s².)
- A
2,400 W
- B
30 W
- C
1,920 W
- D
300 W
- A
Efficiency
1 card- 31
An electric motor draws 500 J of electrical energy and lifts a load that gains 350 J of potential energy. What is its efficiency, and where did the rest go?
- A
143%; the motor amplified the energy
- B
70%; the remaining 150 J became heat in the windings and bearings and sound
- C
70%; the remaining 150 J was destroyed
- D
30%; only the wasted part counts
- A
Specific heat capacity
1 card- 32
Why does the sea stay cool on a hot afternoon when the sand beside it is too hot to walk on?
- A
Sand is dark and absorbs more light than water
- B
Water's specific heat capacity is about five times that of sand, so the same sunlight raises its temperature far less
- C
The sea is constantly cooled by evaporation and nothing else
- D
Water reflects all the sunlight
- A
Ohm's law
1 card- 33
A 12 V battery is connected across a 4 Ω resistor. What current flows?
- A
0.33 A
- B
48 A
- C
8 A
- D
3 A
- A
Series and parallel circuits
2 cards- 34
Two 6 Ω resistors are connected in parallel. What is their combined resistance?
- A
3 Ω
- B
12 Ω
- C
6 Ω
- D
0.33 Ω
- A
- 35
A string of old-style Christmas lights goes completely dark when one bulb fails. What does that tell you about the circuit?
- A
The bulbs are in series: one broken filament opens the only path for current
- B
The fuse has blown
- C
The bulbs share one filament
- D
The bulbs are in parallel: the failure short-circuits the others
- A
Electric power
2 cards- 36
An electric kettle rated 2,300 W runs on a 230 V supply. What current does it draw, and what resistance does its element have?
- A
0.1 A and 2,300 Ω
- B
10 A and 2,300 Ω
- C
23 A and 10 Ω
- D
10 A and 23 Ω
- A
- 37
Why is electricity transmitted across the country at hundreds of thousands of volts rather than at the 230 V used in homes?
- A
High-voltage electricity is safer to handle
- B
High voltage travels faster through the wires
- C
Transformers only work at high voltage
- D
At high voltage the same power needs far less current, and the heat lost in the cables goes as the square of the current
- A
Kilowatt-hour
1 card- 38
A 2 kW heater runs for 3 hours. Electricity costs 30 cents per kilowatt-hour. What does it cost?
- A
$1.80
- B
$18.00
- C
$0.20
- D
$0.60
- A
Wave
1 card- 39
A radio station broadcasts at 100 MHz. What is the wavelength of its signal? (Speed of light $3 \times 10^8$ m/s.)
- A
300 m
- B
30 m
- C
3 m
- D
0.3 m
- A
Speed of light
1 card- 40
Sunlight takes about 8 minutes to reach Earth. If the Sun vanished this instant, when would we notice?
- A
About 8 minutes for the light, but the orbit would change instantly
- B
Immediately: gravity acts instantly
- C
Immediately in darkness, but Earth would keep orbiting for 8 minutes
- D
About 8 minutes from now, for both its light and its gravity
- A
Nuclear fission
1 card- 41
In a nuclear reactor, where does the energy actually come from?
- A
Electrons are stripped from the uranium atoms
- B
Chemical bonds between uranium atoms break
- C
A tiny fraction of the nucleus's mass is converted to energy, according to $E = mc^2$
- D
Uranium burns in oxygen at very high temperature
- A
Half-life
1 card- 42
A hospital has a 40 mg sample of technetium-99m, half-life 6 hours. How much remains after one day?
- A
10 mg
- B
0 mg
- C
20 mg
- D
2.5 mg
- A
Electromagnetic spectrum
1 card- 43
Which carries more energy per photon: red light or ultraviolet?
- A
They are equal: all photons carry the same energy
- B
Red light: it is hotter
- C
Red light: it has the longer wavelength
- D
Ultraviolet: photon energy rises with frequency, and UV has the higher frequency
- A
Sound
1 card- 44
Can sound travel through space?
- A
Yes: it travels as radio waves
- B
Yes, but very slowly
- C
No, because it is too cold
- D
No: sound is a pressure wave and needs a medium; the vacuum of space has nothing to carry it
- A
Lunar phase
1 card- 45
What causes the phases of the Moon?
- A
The Moon rotates and shows us its dark side
- B
Earth's shadow falls across the Moon
- C
Clouds in the Moon's atmosphere
- D
We see varying amounts of the Moon's sunlit half as it orbits Earth
- A
End of deck · 45 cards