Practice MCQs For Mass, Weight and Density, Work, Energy and Power

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This quiz contains practice questions for GCE ‘O’ level topics: Mass, Weight and Density, Work, Energy and Power. There are explanations for some of the questions after you submit the quiz. If you could not figure out why a particular option is the answer, feel free to drop a comment below or ask a question in ‘O’ & ‘A’ Level Discussion section of the forum. If you wish to contribute questions to this quiz, please contact us.

The quiz comprises of 10 questions, which are randomly selected from a large pool of questions. After completion, you can refresh the page and try the quiz again for a new set of 10 questions.

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1. Ten identical steel balls, each of mass 27 g, are immersed in a measuring cylinder containing 20 $cm^{3}$ of water.

The reading of the water level rises to 50 $cm^{3}$.

What is the density of the steel?
2. A mass hangs on a string fixed at point P. It starts from position 1 and swings to the furthest position on the opposite side, position 2. It then oscillates several times with decreasing amplitude before ending at position 3.

mass on a stringWhere does the ball have the most kinetic energy?
3. The diagram shows a material with dimensions 5 cm $ \times $ 4 cm $ \times $ 2 cm. It has a mass of 100g.

What is the density of the material?
4. When a nucleus of Uranium-235 absorbs a neutron, nuclear fission occurs. In a typical reaction, the total mass decreases by $3 \times 10^{-28}$ kg.

Given that the speed of light c is $3 \times 10^{8}$ m/s, approximately how much energy is released?

 

Hint: (Use Einstein's mass equivalence equation: $E = mc^{2}$)
5. A girl of weight 500 N runs up a flight of stairs in 10 seconds. The vertical height of the stairs is 5 m.

What is the average power developed by the girl?
6. A rock on the Moon has a mass of 0.5 kg. It is brought to the Earth where the gravitational field is stronger. On the Earth, the rock will have _________ .
7. A machine is able to lift 200 kg of bricks vertically up to a height of 30 m above the ground in 50 s. What is the power of the machine? (Take the acceleration due to gravity, $g$, to be $10 \text{ ms}^{-2}$.)
8. A builder carrying six bricks climbs a ladder. Each brick weighs 25 N and the builder climbs a vertical distance of 4.0 m in 8.0 seconds.

What is the average power used to raise the bricks?
9. Which statement is correct about the position of the centre of gravity of a uniform solid?

The centre of gravity of a uniform solid
10. A boy, who weighs 50 N, runs up a flight of stairs 6.5 m high in 7 seconds.

How much power does he develop?

 

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20 thoughts on “Practice MCQs For Mass, Weight and Density, Work, Energy and Power”

  1. Consider a stationary box at height x. The block is lifted by a student such that it comes to a rest at higher height y.

    Consider the following discussion between two students:

    Student 1: I exert an upward force on the box, which moves upward, so I do positive work on the box. The Earth exerts a downward force, so it does negative work on the box. The box begins and ends at rest, so its kinetic energy hasn’t changed. That means that the net work on the box is zero, so the work on the box by my hand and the work on the box by the Earth must have the same absolute value.

    Student 2: But the box has moved upward, so its potential energy has increased. That means that the net work on the block must be positive, so the work on the box by your hand must be greater than the work on the box by the Earth.

    What can you say about the reasoning given by the two students?
    1. They are both incorrect.
    2. Student 2 is correct and student 1 is incorrect.
    3. They are both correct.
    4. Student 1 is correct and student 2 is incorrect.

    why is the answer 4

    Reply
    • student 2 is incorrect as they say that the work done on the box by the hand must be greater than the work done on the box by gravity, which, if it was true, would mean that the box is accelerating. Student 1 however says that the work done on the box must be zero, and have the same value.

      idk just guessing

      Reply
  2. volume of ten steel balls =50-20=30
    volume of a steel ball=30/10=3 cm^3
    mass of a steel ball=27 g
    density=mass/volume=27g/3cm^3=9g/cm^3

    Reply
  3. I also have a question.
    Which of these have a greater refractive index and why?
    A) water
    B)ice

    1)water, since it has more density
    2) ice, since it has more density
    3) water, since it has less density
    4) ice, since it has less density

    Reply
  4. 1. Ten identical steel balls, each of mass 27 g, are immersed in a measuring cylinder containing 20 cm3cm3 of water.
    The reading of the water level rises to 50 cm3 .

    What is the density of the steel?

    a)8.1 g/cm3
    b)13.5 g/cm3
    c)9.0 g/cm3[correct]
    d)0.90 g/cm3
    The volume of the ten steel balls is 50 – 20 = 30 . Density is calculated using Density= mass/volume.

    Can someone explain to me why c is correct?
    But I think d is correct.

    Reply
  5. There is a problem with these tests….. I tick the correct answers but when they show the result, all the answers that I ticked are shown wrong. I mean, they do not check correctly what I ticked. e.g if I ticked the answer c, which is correct, then instead of giving me marks, they think I ticked something else for example d and them tell me the correct answer is c which I eventually did tick.!!!! I AM CONFUSED!

    Reply

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