Grade 12 Physics 2015 Quiz

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Created on August 04, 2020

G12 Physics 2015

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The diagram shows particle P moving in a circular path at a constant speed.

A force of constant size acts on P in the direction of motion.

A force of constant size acts on P towards 0.

The force of P varies in size as it moves around the circle.

There is no resultant force acting on P

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A light rigid rod 40cm long is supported horizontally at its end by two vertical strings.
A weight of 50N is attached to the rod a distance of 10cm from end x as shown.

12.5N

25.5N

50.0N

400.5N

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An Eskimo stands on snow wearing snow shoes. The mass of the Eskimo is 40kg and
the snow shoes have a total area of 5m2 in contact with the snow (gravitational field
strength is 10N/kg).
What pressure does the Eskimo exert on the snow?

8.0N/m²

40.0N/m²

50.0N/m²

80.0N/m²

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A simple machine of velocity ratio 5 is used to lift a load of 600N through a vertical
distance of 20m. If the machine is 80% efficient, what is the effort applied?

150N

200N

300N

400N

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The diagram shows an object of total mass 2500kg descending from rest at the top
of a steep incline.

1.875 × 10⁶J

2. 750 × 10⁶J

7.500 × 10⁶J

8.750 × 10⁶J

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The temperature at which the particles which make up substances have their lowest
possible energy is ....

0°C.

-100°C.

-273K.

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A piece of aluminium of mass 0.5kg is heated to 100°C and then placed in 0.4kg of
water at 10°C. If the resulting temperature is 30°C, what is the specific heat capacity
of aluminium? Take specific heat capacity of water as 4 200J/kg°

960 J/kg°C

4 200 J/kg°C

8 400 J/kg°C

33 600 J/kg°C

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A boy standing in wind in a wet swimming suit feels much colder than when the suit
was dry. This is because ....

he loses latent heat as water evaporates from his body.

he gains latent heat as water evaporates from his body.

the wet swimming suit conducts more heat than the dry one.

his body is now directly in contact with cold air.

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The diagram shows two metal bars x and y of the same size. The bars are initially at
the same temperature.

Bar X is a better conductor of heat than bar Y.

Bar Y is a better conductor of heat than bar X.

The two metal bars conduct heat equally.

End B of bar Y is colder than end B of bar X.

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Which property of waves is being demonstrated in the diagram below?

Refraction

Diffraction

Bending of waves

Constructive interference

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A note of sound is produced on a keyboard. Its characteristics are that it is louder
and has lower pitch. Which of the following waveforms represents this note of
sound?

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The diagram shows a girl standing 150m in front of a tall building. She fires a shot
using a starting pistol. A boy, standing 350m from the girl, hears two bangs 1 second apart.

300m/s

350m/s

650m/s

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A girl stands 3.0m in front of a plane mirror as shown below.

3.0m

3.7m

4.5m

6.0m

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The diagram below shows a ray of light entering a glass block of refractive index
1.51.

20°

30°

35°

60°

21 / 40

A pupil breaks down a bar magnet into three equal parts without disturbing its
position as shown below.

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Which statement describes an example of induced magnetism?

Two north poles repel each other, but a north pole attracts a south pole.

A bar magnet swinging freely comes to rest pointing north-south.

A bar magnet attracts a piece of soft iron.

A bar magnet loses its magnetism if it is repeatedly dropped.

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The diagram below shows a charging circuit for an accumulator.

When freshly made, each accumulator has an e.m.f of about 12V.

X represents the positive (red terminal) side of the accumulator.

Y represents the positive (red terminal) side of the accumulator.

X represents the negative (black or blue terminal) side of the accumulator.

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In the circuit shown below, resistors P and Q act as a potential divider used to
control the speed of a motor.

resistance of the motor.

e.m.f of the battery.

potential difference across the motor.

current through P.

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The diagram below shows identical lamps X and Y connected in series with a
battery. The lamps light with normal brightness.

Brighter than normal.

Normal as before.

Dimmer than normal.

Very dim (cannot be seen)

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Which circuit diagram can be used to verify ohm’s law?

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An immersion water heater is marked 240V, 2kW and it is operated for 180 minutes.
If the cost of 1 unit (kWh) of electricity is K5.00 what is the cost of running this
water heater?

K6.00

K10.00

K15.00

K30.00

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The diagram below shows the variation of e.m.f of a simple a.c generator with time.

4 s

4Hz

0.75 Hz

0.25 Hz

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A moving coil loudspeaker ....

receives sound from a microphone.

receives sound from the speaker through the cables.

receives audio-frequency electric currents produced in the wires.

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Which statement is correct? Heat engines ....

are always more than 100% efficient.

change fuel into mechanical energy.

change heat energy into mechanical energy.

change mechanical energy into heat energy.

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A capacitor of capacitance 10 × 10-⁶F is charged by a battery of 6V. How much
charge is stored on each plate?

2 × 10-⁶C

9 × 10-⁵C

6 × 10-⁵C

1 × 10-⁴C

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Which of the following is a basic memory unit used in computers?

Bistable

Astable

Control unit

Arithmetic logic unit

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Thermionic emission is the loss of ....

heat by hot objects.

electrons by protons.

electrons by heated metal surfaces.

heat by electrons.

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Which of the following can be used to produce a series of voltage pulses?

Voltmeter

Cathode ray oscillography

Bistable circuits

Astable circuits

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. A radioactive substance has a half-life of 15 minutes. If the original mass is 10kg,
what mass remains undecayed after 1 hour?

625g

740g

820g

960g

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The diagram shows a sketch computer system.

Scanner

Printer

CPU

External drive

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How do the nucleon number and proton number of two isotopes of an element
compare?

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