Class 9 > Unit # 08: Energy Sources & Transfer of Energy > Textbook M.C.Qs

Work, Energy and Power Quiz

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1. If force of 6N displaces an object 2m in the direction of force, then work done will be ___.

a) 0 b) 12 Joule c) 3 Joule d) Both b and c

Explanation: Work done is calculated using the formula W = F x d. Here, W = 6 N x 2 m = 12 Joules.

2. If a body of mass 1 kg is moving with velocity of 1m/sec then K.E of the body will be

a) 0 Joules b) 0.25 Joules c) 0.5 Joules d) 1 Joule

Explanation: Kinetic Energy formula is K.E = (1/2) * m * v^2. Substituting values: (1/2) x 1 kg x (1 m/s)^2 = 0.5 Joules.

3. If a machine performs 20J of work in 10sec then its power is ________.

a) 200 watt b) 20 watt c) 2 watt d) 0.2 watt

Explanation: Power is work done per unit time (P = W / t). Thus, P = 20 J / 10 s = 2 Watts.

4. A body of mass 1kg is lifted through a height of 1m. The energy possessed in the body will be _______. (consider g = 10 ms^-2)

a) 1J b) 10 Joule c) 100 Joule d) 1000 Joule

Explanation: Gravitational potential energy is given by P.E = m * g * h. Hence, P.E = 1 kg x 10 m/s^2 x 1 m = 10 Joules.

5. The energy released during fission or fusion reaction is called ____________.

a) Solar energy b) Geothermal energy c) Tidal energy d) Nuclear energy

Explanation: Nuclear fission (splitting of atoms) and nuclear fusion (combining of atoms) release massive amounts of energy known as nuclear energy.

6. Which is the renewable source of energy?

a) Solar and wind b) Coal c) Natural gas d) Petroleum

Explanation: Solar and wind energy are naturally replenished and inexhaustible, unlike fossil fuels (coal, natural gas, petroleum).

7. The ratio of output to input is called:

a) Energy b) Work c) Power d) Efficiency

Explanation: Efficiency is defined as the ratio of useful energy output (or power output) to the total energy input.

8. Work done per unit time is called __________.

a) Efficiency b) Energy c) Power d) Force

Explanation: Power measures how fast work is done, defined mathematically as P = W / t.

9. Coal, gas and oil are all examples of _________.

a) Tidal energy b) Nuclear energy c) Fossil fuel energy d) Biomass energy

Explanation: Coal, natural gas, and oil are formed from the remains of ancient organisms over millions of years, classifying them as fossil fuels.

10. ____________ is not a renewable source of energy.

a) Solar energy b) Coal c) Wind energy d) Geothermal energy

Explanation: Coal is a non-renewable resource because reserves are limited and take millions of years to form.