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

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1. The mass of a paper-clip is 0.50 g and the density of its material is $8.0 \text{ g cm}^{-3}$. The total volume of a number of paper-clips is $20 \text{ cm}^{3}$.

How many paper-clips are there?

160

240

320

2. 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: $E = mc^{2}$)

$2 \times 10^{-13}$ J

$3 \times 10^{-5}$ J

$9 \times 10^{-20}$ J

$3 \times 10^{-11}$ J

3. A car is driven along a level road. The total energy input from the petrol is 60 kJ, and the car wastes 45 kJ of energy.

What is the efficiency of the car?

45%

25 %

75 %

15 %

4. 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.

Where does the ball have the most kinetic energy?

The last time at position 3

At position 1

The first time at position 3

At position 2

5. Which statement is correct about the position of the centre of gravity of a uniform solid?

The centre of gravity of a uniform solid

depends on the mass of the solid.

is fixed and on the solid itself.

depends on the density of the solid.

is fixed and may be outside the body.

6. A student does an experiment to estimate the density of an irregularly-shaped stone.

Which items of equipment are needed?

a ruler and a measuring cylinder containing water

a balance and a ruler

a balance and a measuring cylinder containing water

only a measuring cylinder containing water

7. A 2 kg mass is moving at constant speed.

The kinetic energy of the mass is 400 J.

What is the speed of the mass?

$0.4 \text{ ms}^{-1}$

$20 \text{ ms}^{-1}$

$200 \text{ ms}^{-1}$

$400 \text{ ms}^{-1}$

8. In an emergency, a car screeched to a stop to avoid a collision with a van that had stopped suddenly in front of it. What is the energy change involved in this process?

Kinetic energy is converted to sound energy only.

Kinetic and potential energy are covnerted to heat and sound energy.

Potential energy is converted to heat, sound and kinetic energy.

Kinetic energy is converted to heat and sound energy.

9. An object is lifted at constant speed through a distance h metres above the ground in t seconds. The potential energy gained by the object is equal to

force acting on the object

work done X time

work done on the object minus kinetic energy of the object

work done on the object

10. A pendulum is released from rest and undergoes simple harmonic motion (its oscillating). The starting point of the pendulum is point A and the lowest point of the oscillation is point B. By comparing the pendulum's state at the point A and point B of the oscillation, what can you say about the

total energy of the Earth-pendulum system and
the total energy of the system consisting of the pendulum only

(Neglect air resistance)

The total energy of the Earth-pendulum system is the same at both points. The total energy of the system consisting of the pendulum is higher at A.

The total energy of the Earth-pendulum system is the same at both points. The total energy of the system consisting of the pendulum is higher at B.

The total energy of the Earth-pendulum system is the same at both points. The total energy of the system consisting of the pendulum is the same at both points.

The total energy of the Earth-pendulum system is higher at A. The total energy of the system consisting of the pendulum is the same at both points.

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

Mini Physics

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