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 71: The percentage of the original nuclei of the sample of a radioactive substance left after 5 half - lives is
Options:
A) 8%
B) 5%
C) 3%
D) 1%
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The correct answer is C .
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Question 72:
Fig 1 is a graph of force against extension for a spiral spring, the force constant of the spring is given by the
Options:
A) slope of the linear prtion of the graph
B) length of the linear portion of the graph
C) area under the linear portion of the graph
D) area under the entire graph
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The correct answer is A .
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Question 73:
The density of a solid is defined as the
Options:
A) mass of the solid compared to the mass of an equal volume of water
B) amount of water displaced when a unit mass of thesolid is immersed in it
C) weight per unit volume of the solid
D) volume per unit mass of the solid
E) mass per unit volume of the solid
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The correct answer is E .
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Question 74: Which of the following statements are true of the law of universal gravitation?
Options:
A) any two bodies attract each other with a force which is proportional to the difference of their masses
B) any two bodies attract each other with a force which is inversely proportional to the square of the distance between them
C) any two bodies attract each other with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them
D) any two bodies attract each other with a force which is proportional to the square of the distance between them
E) any two bodies attract each other with a force which is proportional to the sum of their masses
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The correct answer is C .
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Question 75:
A 400 N box is being pushed across a level floor at a constant speed by a force P of 100 N at an angle of 30.0° to the horizontal, as shown in the the diagram below. What is the coefficient of kinetic friction between the box and the floor?
Options:
A) 0.19
B) 0.24
C) 0.40
D) 0.22
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The correct answer is A .
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Question 76:
In semi-conductor, the carriers of current at room temperature are
Options:
A) electrons only
B) electrons and holes
C) holes only
D) electron and ions
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The correct answer is B .
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Question 77: A short chain is sometimes attached to the back of a petrol tanker to?
Options:
A) generate more friction
B) ensure the balancing of the tanker
C) caution the driver when overspeeding
D) conduct excess charges to the car
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The correct answer is D .
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Question 78:
A sonometer wire is vibrating at frequency fo. If the tension in the wire is doubted while the length and the mass per unit length are kept constant, the new frequency of vibration is
Options:
A) fo/2
B) 2fo
C) fo/√2
D) fo√2
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The correct answer is D .
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Question 79:
A simple pendulum, has a period of 5.77 seconds. When the pendulum is shortened by 3 m, the period is 4.60 seconds. Calculate the new length of the pendulum
Options:
A) 5.23 m
B) 6.42 m
C) 4.87 m
D) 7.26 m
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The correct answer is A .
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Question 80: The speed of light in vacuum is 3.0 x 108ms-1. If the refractive index of a transparent liquid is , then the speed of light in the liquid is
Options:
A) 0.44 x 10 8ms-1
B) 2.25 x 10 8ms-1
C) 3.0 x 10 8ms-1
D) 4.0 x 10 8ms-1
E) 4.33 x 10 8ms-1
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The correct answer is B .