Physics is the science that studies the nature and properties of matter and energy. It covers topics like motion, heat, light, sound, electricity, magnetism, and the structure of atoms.
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Question 81: An electric kettle, connected to a 240V mains, produces 6.0 x 105J of heat energy to boil a quantity of water in 5 minutes. Find the resistance of the kettle.
Options:
A) 14.4
B) 28.8
C) 144
D) 288
E) 2880
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The correct answer is B .
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Question 82: A gramophone record takes 5s to reach its constant angular velocity of 4 rads-1 from rest. Find its constant angular acceleration.
Options:
A) 0.4 rads-2
B) 0.8 rads-2
C) 1.3 rads-2
D) 20.0 rads-2
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The correct answer is B .
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Question 83:
The diagram above shows a velocity - time graph. The statement that is true about this motion is that the car
Options:
A) has no acceleration between point F and G
B) decelerates between F and H
C) has a constant soeed between points E and F
D) Accelerates between points F and G
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The correct answer is A .
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Question 84:
What type of reaction is represented by the following scheme?
+ -----> + + energy
Options:
A) fusion reaction
B) fission reaction
C) Chain reaction
D) radioactive decay
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The correct answer is A .
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Question 85: A force F required to keep a 5 kg mass moving round a cycle of radius 3.5 m at a speed of 7 ms-1. What is the speed, if the force is tripled?
Options:
A) 4.0 ms-1
B) 6.6 ms-1
C) 12.1 ms-1
D) 21.0 ms-1
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The correct answer is C .
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Question 86: A bar magnet is most effectively demagnetized by
Options:
A) placing it in a N - 5 position and hitting it with a hammer
B) subjecting it to an electric current from a battery
C) bringing its north pole in contact with the north pole of a very strong magnet
D) heating the magnet
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The correct answer is A .
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Question 87: The echo of a sounder from the bottom of an ocean is heard 2.5 seconds later. If the speed of sound in water is 1,400ms-1, the depth of the ocean is
Options:
A) 1,750m
B) 3,500m
C) 1,400m
D) 2,800m
E) 2,100m
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The correct answer is A .
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Question 88: When the volume of a given mass of gas is halved and its temperature doubled, the pressure
Options:
A) remains constant
B) increases by a factor of 4
C) increases by a factor of 3
D) decreases by a factor of 4
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The correct answer is B .
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Question 89: The force on a current carrying conductor in a magnetic field is greatest when the
Options:
A) conductor makes an angle of 60° with the field
B) force is idependent of the angles between the fields and the conductor
C) conductor is parallel with the field
D) conductor is at right angle with the field
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The correct answer is D .
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Question 90: Two similar kettles containing equal masses of boiling water are placed on a table. If the surface of one is highly polished and the surface of the other is covered with soot, Which of the following observations is correct
Options:
A) The two kettles will cool down at the same rate
B) the polished kettle cools down more quickly by conduction
C) the kettle covered with soot cools down more quickly because it is a good radiator
D) the kettle covered with soot cools down more quickly by the process of heat convection
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The correct answer is C .