CBSE Questions for Class 9 Physics Work And Energy Quiz 3 - MCQExams.com

SI unit of electrical energy is
  • Joule
  • Kilowatt hour
  • KiloJoule
  • Watt hour
The hydroelectric plants do not produce electricity, if the water level in the dam is less than 34 m.
  • True
  • False
  • Ambiguous
  • Data insufficient
What is kinetic energy?
  • Energy possessed by a body by the virtue of its motion
  • Energy possessed by a body by the virtue of its shape
  • Energy possessed by a body by the virtue of its size
  • None
Write true or false for the following statements :
Electric power is also called BOTU. 
  • True
  • False
A body at rest can't have
  • Momentum
  • Kinetic energy
  • Both $$a$$ & $$b$$
  • None
There are $$5$$ tube-lights each of $$40\ W$$ in a house. These are used on an average for $$5\ hrs/day$$. In addition, there is an immersion heater of $$1500\ W$$ used on an average for $$1\ hr/day$$. The number of units of electricity that are consumed in a month of $$30\ days$$ is:
  • $$25\ units$$
  • $$50\ units$$
  • $$75\ units$$
  • $$100\ units$$
Water stored in a dam possesses:

  • no energy
  • electrical energy
  • kinetic energy
  • potential energy
The electrical energy in kilowatt hours consumed in operating ten $$50\ W$$ bulbs for $$10\ hrs/day$$ in a month of $$30\ days$$ is
  • $$1500$$
  • $$15000$$
  • $$15$$
  • $$150$$
A pump delivers water at the rate of $$2400\ litres$$ in $$6\ minutes$$ over a head of $$12\ m$$. If $$g = 10 m/s^{2}$$, then its power is:
  • $$200\ W$$
  • $$800\ W$$
  • $$240\ W$$
  • $$24\ kW$$
A man pushes a wall and fails to displace it. He does :
  • Negative work
  • Positive but not maximum work
  • Maximum work
  • No work at all
A car is accelerated on a leveled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
  • does not change
  • becomes twice to that of initial
  • becomes 4 times that of initial
  • becomes 16 times that of initial
A rain drop of mass (1/10) gram falls vertically at constant speed under the influence of the forces of gravity and viscous drag. In falling through 100 m, the work done by gravity is
  • 0.98 J
  • 0.098 J
  • 9.8 J
  • 98 J
A house is fitted with ten lamps of each $$60\ W$$. Each lamp burns for $$5\ hrs$$ a day on an average. The cost of consumption in a month of $$30\ days$$ at $$80$$ rupees per unit is:
  • $$Rs. 152$$
  • $$Rs. 252$$
  • $$Rs. 352$$
  • $$Rs. 452$$
A coconut fruit hanging high in a palm tree has ......... owing to its location.
  • Free energy
  • Kinetic energy
  • Activation energy
  • Potential energy
A girl is carrying a school bag of $$3\ kg$$ mass on her back and moves $$200\ m$$ on a leveled road. The work done against the gravitational force will be ($$g = 10\ m/s^{2}$$) :
  • $$6\times 10^{3}\ J$$
  • $$6\ J$$
  • $$0.6\ J$$
  • $$Zero$$
  • None of these
A girl of mass 40 kg climbs 50 stairs of average height 20 cm each in 50 s. Find the power of the girl. $$(g = 10 m\:s^{-2})$$



  • $$50\ W$$
  • $$20\: W$$
  • $$80\ W$$
  • $$500\: W$$
A 220 V, 100 W bulb is connected to a 110 V source. Calculate the power consumed by the bulb.

  • 10 W
  • 15 W
  • 20 W
  • 25 W
If an electric iron of $$1200 \ W$$ is used for $$30 \ minutes$$ everyday, find electric energy consumed in the month of April.

  • $$12\  kWh$$
  • $$18 \ kWh$$
  • $$36\  kWh$$
  • $$6\  kWh$$
   Answer question numbers 72 and 73 based on the following information.
Solar surface radiates energy uniformly at a rate of $$4 \times  10^{26}W$$. This energy spreads or distributes uniformly and normally outwards.

Considering Earth and the Sun to be spherical object, the amount of radiant energy received by the Earth per second is nearly

  • $$1360 \:W.$$
  • $$1.75 \times 10^{17}\:W$$
  • $$3.5 \times 10^{17}\:W$$
  • $$7 \times 10^{17}\:W$$
A girl having a mass of $$35\ kg$$ sits on a trolley of mass $$5\ kg$$. The trolley is given an initial velocity of $$4\ ms^{-1}$$ by applying a force. The trolley comes to rest after traversing a distance of $$16\ m$$. How much work is done on the trolley? 
  • $$0\ J$$
  • $$320\ J$$
  • $$120\ J$$
  • $$250\ J$$
 In a hydro power plant:
  • Potential energy possessed by stored water is converted into electricity
  • Kinetic energy possessed by stored water is converted into potential energy
  • Water is heated to produce electricity
  • Water is converted into steam to produce electricity
$$1kWh= $$ _________?
  • $$3600000\ J$$
  • $$10000\ J$$
  • $$4.2\ J$$
  • $$25000\ J$$
How much work they do in just holding it ?
  • 250 J
  • 2500 J
  • 0 J
  • 625 J
Kilowatt is the unit of electrical _______ but kilowatt-hour is the unit of electrical _______.
  • Power, Energy
  • Power, Electric potential
  • Power, Current
  • Energy, Power
An 800 g ball is pulled up a slope as shown in the diagram. Calculate the potential energy it gains.

85197.jpg
  • 1.96 J
  • 1.568 J
  • 7.84 J
  • 1.225 J
Kilowatt-hour is the unit of :
  • potential difference.
  • electric power.
  • electrical energy.
  • charge.
When velocity of a moving object is doubled its:
  • acceleration is doubled
  • momentum becomes four times more
  • kinetic energy is increased to four times
  • potential energy is increased
An electric kettle is rated as $$2.5\ kW, \ 250\ V$$. Find the cost of running the kettle for two hours at $$60\ \text{paisa}/\text{unit}$$.
  • $$Rs\ 6$$
  • $$Rs\ 3$$
  • $$Rs\ 9$$
  • $$Rs\ 1$$
An air conditioner is rated $$240\ V, 1.5\ kW$$. The air conditioner is switched on $$8\ hrs$$ each day. What is electrical energy consumed in $$30\ days$$?
  • $$2.88\ kWh$$
  • $$360\ kWh$$
  • $$120\ kWh$$
  • $$240\ kWh$$
Unit of work in MKS system is
  • Calorie
  • Newton
  • Joule
  • Watt
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