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ZIMSEC O Level · 4023/2

Physics Paper 2 Specimen 2021

Questions
33
Total marks
123
Time allowed
120 min
Syllabus code
4023/2

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Questions
33
Pass mark
20
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Answer every question in the printed order, get marked at the end, then see the answers.

The questions

Question 101

[1 marks]Using a micrometer screw gauge to measure the diameter of a wire
An instrument has a spindle, an anvil, a sleeve scale marked in millimetres, and a thimble scale, and includes a ratchet to avoid over-tightening on the object being measured. What is this instrument called?

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Question 102

[1 marks]Using a micrometer screw gauge to measure the diameter of a wire
A micrometer screw gauge used to measure the diameter of a wire has a sleeve (main) scale reading of 5.5 mm, and its thimble scale reads 0.12 mm at the datum line. What is the total diameter reading?

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Question 103

[1 marks]Using a micrometer screw gauge to measure the diameter of a wire
A precaution that should be taken when using a micrometer screw gauge to measure the diameter of a wire is to...
  1. Atighten the spindle as hard as possible by hand for a firmer grip.
  2. Balways read the scale from an angle, never directly from the front.
  3. Cignore any zero error, since it cancels out automatically.
  4. Duse the ratchet to avoid over-tightening the spindle onto the wire.

Question 201

[1 marks]Defining velocity and graphing the motion of a decelerating car
State the definition of velocity.

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Question 202

[1 marks]Defining velocity and graphing the motion of a decelerating car
A car travels at a constant speed of 10 m/s for 8.0 s, and is then brought to rest in 4.0 s by a constant braking force. What is the total distance travelled by the car over the whole 12 s journey?
  1. A60 m
  2. B80 m
  3. C100 m
  4. D120 m

Question 301

[1 marks]Non-renewable vs renewable energy sources, and energy conversions at Hwange Thermal Power Station
State one non-renewable source of energy.

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Question 302

[1 marks]Non-renewable vs renewable energy sources, and energy conversions at Hwange Thermal Power Station
Charcoal is considered a renewable source of energy because it...
  1. Ais found in unlimited underground reserves, unlike coal.
  2. Bproduces no carbon dioxide when it is burned.
  3. Ccomes from trees, which can be regrown or replanted.
  4. Ddoes not need any natural process in order to form.

Question 303

[1 marks]Non-renewable vs renewable energy sources, and energy conversions at Hwange Thermal Power Station
At Hwange Thermal Power Station, chemical energy from coal is converted to thermal energy (by heating the coal to produce steam), which is then converted to kinetic energy that drives the turbines. What form of energy is produced next?

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Question 401

[1 marks]Renewable resources, multi-cylinder engines, and worn fuel jets
State one renewable energy resource.

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Question 402

[1 marks]Renewable resources, multi-cylinder engines, and worn fuel jets
A key advantage of using multiple cylinders (rather than a single cylinder) in an engine is that it...
  1. Aeliminates the need for a cooling system.
  2. Bgives smoother running of the engine through more even firing and power distribution.
  3. Cincreases the compression ratio of the fuel-air mixture.
  4. Dreduces the overall weight of the engine.

Question 403

[1 marks]Renewable resources, multi-cylinder engines, and worn fuel jets
Worn out fuel jets in an engine reduce the engine's efficiency because they...
  1. Aincrease the compression ratio, causing pre-ignition.
  2. Bblock the exhaust valve, preventing fumes from escaping.
  3. Creduce the voltage produced by the spark plug.
  4. Dlet through the wrong (limited) amount of fuel, causing incomplete combustion.

Question 501

[1 marks]Current in a two-bulb circuit, and the effect of closing a parallel switch
A circuit has a 4.5 V cell connected in series with two identical bulbs, bulb 1 and bulb 2, each of resistance 5 ohms. A switch in parallel with bulb 1 is open. Calculate the current I in the circuit when the bulbs are at maximum brightness.
  1. A0.45 A
  2. B1.8 A
  3. C0.045 A
  4. D0.9 A

Question 502

[1 marks]Current in a two-bulb circuit, and the effect of closing a parallel switch
In the same circuit (a 4.5 V cell in series with two identical 5 ohm bulbs, bulb 1 and bulb 2, and a switch connected in parallel with bulb 1 only, initially open), the switch is then closed. What happens to bulb 1?
  1. Ait stops lighting, since it is now short-circuited by the closed switch.
  2. Bit flickers, due to the switching action.
  3. Cit becomes brighter, since more current now flows through it.
  4. Dit stays the same, since the switch does not affect it.

Question 503

[1 marks]Current in a two-bulb circuit, and the effect of closing a parallel switch
In the same circuit, when the switch (connected in parallel with bulb 1 only) is closed, state what happens to the current I from the cell: does it increase, decrease, or stay the same?

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Question 601

[1 marks]Completing a ray diagram for a plane mirror image, and stating the image's properties
Which of the following is NOT a property of the image formed by a plane mirror?
  1. Ait is magnified, larger than the object.
  2. Bit is virtual.
  3. Cit is laterally inverted.
  4. Dit is the same size as the object.

Question 701

[1 marks]Defining radioactive decay, half-life calculation, and short-half-life isotopes in medicine
Define the term radioactive decay.

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Question 702

[1 marks]Defining radioactive decay, half-life calculation, and short-half-life isotopes in medicine
An isotope has an initial mass of 64 mg and a half-life of 4 days. What mass of the isotope remains after 16 days?
  1. A4 mg
  2. B64 mg
  3. C16 mg
  4. D8 mg

Question 703

[1 marks]Defining radioactive decay, half-life calculation, and short-half-life isotopes in medicine
Radioactive isotopes with very short half-lives (rather than long half-lives) are preferred for use in medicine because they...
  1. Aare cheaper to produce than long-half-life isotopes.
  2. Bdecay quickly and so do not remain radioactive in the patient's body for long.
  3. Cemit a different, safer type of radiation.
  4. Dare easier to detect using a Geiger counter.

Question 801

[1 marks]Identifying a logic gate from its symbol, its truth table, and a TV anti-theft alarm system
A logic gate has a curved input edge, a pointed output tip, two inputs A and B, and one output. Its output is 1 whenever A, B, or both inputs are 1, and 0 only when both A and B are 0. Name this logic gate.

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Question 802

[1 marks]Identifying a logic gate from its symbol, its truth table, and a TV anti-theft alarm system
A TV anti-theft alarm system has a pressure-sensitive stand: its output is 1 when the TV is on the stand, and 0 when the TV is removed. This output feeds into a NOT gate, whose output drives an alarm bell (the bell rings when the NOT gate's output is 1). What happens when someone removes the TV from the stand?
  1. Athe stand's output becomes 1, so the NOT gate's output becomes 0, and the alarm does not ring.
  2. Bthe stand's output becomes 0, so the NOT gate's output becomes 1, and the alarm rings.
  3. Cthe NOT gate's output becomes 0, so the alarm remains silent.
  4. Dthe stand's output stays at 1, so the alarm does not ring.

Question 803

[1 marks]Identifying a logic gate from its symbol, its truth table, and a TV anti-theft alarm system
For an OR gate with two inputs, A and B, state the output when A = 0 and B = 0.

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Question 901

[1 marks]Average speed of two boats, a velocity-time graph of a car's journey, circular motion, and terminal velocity of a parachutist
A car's velocity-time graph shows the velocity constant at 10 m/s from t = 15 s (point X) to t = 25 s (point Y). What is the distance travelled by the car between X and Y?
  1. A250 m
  2. B100 m
  3. C150 m
  4. D10 m

Question 902

[1 marks]Average speed of two boats, a velocity-time graph of a car's journey, circular motion, and terminal velocity of a parachutist
On the same graph, the car's velocity increases from 10 m/s at Y (t = 25 s) to 50 m/s at Z (t = 35 s). Calculate the car's acceleration between Y and Z.
  1. A40 m/s^2
  2. B6 m/s^2
  3. C5 m/s^2
  4. D4 m/s^2

Question 903

[1 marks]Average speed of two boats, a velocity-time graph of a car's journey, circular motion, and terminal velocity of a parachutist
An object moving around a circle at a constant speed cannot have a constant velocity because...
  1. Aits speed is actually changing slightly due to friction.
  2. Bits direction of motion is continually changing, and velocity is a vector quantity.
  3. Cthe radius of the circle keeps changing as it moves.
  4. Dacceleration, like speed, is a scalar quantity.

Question 1001

[1 marks]Petrol vs diesel engines, the four-stroke cycle, the carburettor, engine efficiency, and the economic implications of fuel use
Which of the following is a genuine difference between a diesel engine and a petrol engine?
  1. Aa diesel engine has lower maintenance costs than a petrol engine.
  2. Ba diesel engine produces more carbon monoxide than a petrol engine.
  3. Ca diesel engine generates less power than a petrol engine.
  4. Da diesel engine is heavier, while a petrol engine is lighter.

Question 1002

[1 marks]Petrol vs diesel engines, the four-stroke cycle, the carburettor, engine efficiency, and the economic implications of fuel use
State the role of the carburettor in a petrol engine.

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Question 1003

[1 marks]Petrol vs diesel engines, the four-stroke cycle, the carburettor, engine efficiency, and the economic implications of fuel use
The efficiency of an engine is defined as...
  1. Athe ratio of energy output to energy input.
  2. Bthe ratio of energy input to energy output.
  3. Cthe total fuel consumed by the engine per hour.
  4. Dthe maximum speed the engine can reach.

Question 1101

[1 marks]Refractive index, a ray entering and leaving a glass block, critical angle and optical fibres, and correcting long sight
A ray of light travels from air into a glass block, with i as the angle of incidence and r as the angle of refraction. Give the formula for the refractive index of the glass in terms of i and r.

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Question 1102

[1 marks]Refractive index, a ray entering and leaving a glass block, critical angle and optical fibres, and correcting long sight
A ray of light enters a glass block of refractive index 1.5. If the speed of light in air is 300 000 km/s, calculate the speed of light in the glass.
  1. A300 000 km/s
  2. B150 000 km/s
  3. C200 000 km/s
  4. D450 000 km/s

Question 1103

[1 marks]Refractive index, a ray entering and leaving a glass block, critical angle and optical fibres, and correcting long sight
State one advantage of using optical fibres, rather than radio waves, in telecommunications.

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Question 1201

[1 marks]How a transformer works, splitting its core, an ideal transformer calculation, and CRO traces from a model generator
A transformer has an output voltage that is smaller than its input voltage. What type of transformer is this?

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Question 1202

[1 marks]How a transformer works, splitting its core, an ideal transformer calculation, and CRO traces from a model generator
State why a transformer's core is made of soft iron, rather than another magnetic material.

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Question 1203

[1 marks]How a transformer works, splitting its core, an ideal transformer calculation, and CRO traces from a model generator
An ideal transformer steps up a voltage supply from 200 V to 400 V. If the current in the primary coil is 3 A, calculate the current in the secondary coil.
  1. A0.75 A
  2. B6 A
  3. C1.5 A
  4. D3 A

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