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

Two spring of spring constant k and 3k are stretched separately by same force. The ratio of the potential energy stored in them respectively will be 
  • 3 : 1
  • 9 : 1
  • 1 : 3
  • 1 : 9
Which of the following is an example of zero work even when the body suffers a displacement from its initial position?
  • A coolie carrying a load on his head and moving forward on a horizontal road
  • A fielder catching a ball
  • A child pushes a wall
  • A child pulling a toy car
A crane pulls up a car of mass 500kg to a vertical height of 4m. So, work done by the crane is:
  • 19.6J
  • 19.6kJ
  • 19600kJ
  • 4900J
Watt hour represents:
  • Electric energy
  • Current
  • Voltage
  • Power
Unit used in selling electrical energy to consumer is:
  • VoltAmpere
  • Kilowatthour
  • Volt/second
  • None of these
A lamp rated 20W and an electric iron rated 50W are used for 2 hour everyday. Calculate the total energy consumed in 20 days.
  • 14kwh
  • 2.8kwh
  • 40kwh
  • None of these
Number of KWh in 1 Joule.
  • 3.6×106 KWh
  • 2.77×107 KWh
  • 600 KWh
  • 1.6×1019 KWh
Which of these units of energy is the largest?
  • 1 Calorie
  • 1 Joule
  • 1 Erg
  • 1 Kilowatthour
Calculate the power of a source if it produces energy of 250 J in 10 s.
  • 2500 W
  • 2.5 W
  • 25 W
  • Zero
Convert 1 kWh to SI unit of energy.
  • 3.6×106J
  • 3.6×108J
  • 1.8×106J
  • 1.8×108J
Energy consumed in our house has a unit of
  • watts
  • horse power
  • kilowatt-hours
  • none
In which form, the energy is stored in a fuel?
  • Potential energy
  • Thermal energy
  • Kinetic energy
  • Chemical energy
Which one of the following energies cannot be possessed by a body at rest?
  • Potential energy
  • Kinetic energy
  • Thermal energy
  • Magnetic energy
A freely falling object eventually stops on reaching ground. What happens to its potential and kinetic energy while falling?
  • Potential energy decreases and Kinetic energy increases
  • Potential energy increases and Kinetic energy increases
  • Potential energy increases and Kinetic energy decreases
  • None
What is practical unit of power?
  • Watt
  • Kilo watt
  • Horse power
  • None of these
A certain household has consumed 250 units of energy during a month. How much energy is this in joules?
  • 9×1010 J
  • 9×108 J
  • 9×109 J
  • 9×108 J
Find energy in kWh consumed in 10 hours by four devices of power 500 W each?
  • 10 kWh
  • 20 kWh
  • 30 kWh
  • 40 kWh
Smallest commercial unit of energy is
  • Kilowatt hour
  • Watt second
  • Watt hour
  • Watt minutes
Convert 28.8kJ into kilo watt hour.
  • 8×103kwh
  • 8kwh
  • 8×103kwh
  • None of these
An object is dropped from height h=2R on the surface of earth. Find the speed with which it will collide with ground, by neglecting effect of air. [R is radius of earth. Take mass of earth as M]
  • 2GM3R
  • 2GMR
  • GMR
  • GM2
Calculate the monthly bill if a heater of 100 watt is used at the rate of rs. 1 per unit for 1 hour daily.
  • Rs. 200
  • Rs. 6000
  • Rs. 100
  • Rs. 3
Commercial unit of energy is .......................
  • Joule
  • Volt
  • Kilowatt hour
  • Watt second
What is law of conservation of energy?
  • Energy can neither be created nor destroyed. It can only be transformed from one to another.
  • Energy can only be created nor destroyed. It can only be transformed from one to another.
  • Energy can neither be created but can be destroyed. It can only be transformed from one to another.
  • None
An object of mass 40 kg is raised to a height of 5 m above ground. If the object is allowed to fall down find its kinetic energy when it is half-way down.
  • 1960 J
  • 980 J
  • 990 J
  • 1000 J
A weight-lifter lifts a weight of 2000N straight up to a height of 2.25 m in 65 seconds. The weight-lifter kept holding the weight at the same height for the next 4 seconds before dropping it to the floor. Find out how much work did the weight lifter do while holding the weights overhead for 4 seconds ?
  • 1300 Joules
  • 3077 Joules
  • 4500 Joules
  • 8000 Joules
  • No work was done
All types of energy that exist in the nature can be categorized as either kinetic or potential. Choose correct statement regarding the validity of above sentence.
  • This statement is true for thermal and and mechanical, but not elastic
  • This statement is true for all different types of energy
  • This statement is false, except in the case of mechanical energy
  • This statement is never true
A car standing at the top of a hill would be an example of what type of energy?
  • Kinetic
  • Topical
  • Potential
  • Beneficial
  • Residual
Find out work done by a person in pushing a box with a force of 10 N over a distance of 4.0 m in the direction of the force?
  • 0.4 J
  • 4.0 J
  • 40 J
  • 400 J
  • 4000 J
If 120J of work is done in 2 minutes by a water pump, the power of the pump is:
  • 14.4 KW
  • 240 W
  • 60 W
  • 1 W
A father holds his child on his shoulders during a parade. The father does no work during the parade because:
  • No force acts on the child
  • The momentum of the child is constant
  • The potential energy of the child is varying
  • The child's kinetic energy is constant
  • The child's distance from the ground remains the same
0:0:1


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