CBSE Questions for Class 9 Physics Work And Energy Quiz 7 - MCQExams.com

The unit for the measurement of power is:
  • $$Watt$$
  • $$Kilowatt$$
  • $$Kilowatt-hour$$
  • $$Horsepower$$
You lift a suitcase from the floor and keep it on the table. The work done by you on the suitcase depends on
  • the path taken by the suitcase
  • your weight
  • the weight of the suitcase
  • the time taken by you in doing so
A body at rest may have
  • speed
  • velocity
  • energy
  • momentum
The work done in lifting 1 kg mass to a height of 9.8 m is about
  • 1 J
  • 9.8 J
  • $$(9.8)^2 J$$
  • $$\displaystyle \frac{1}{(9.8)^2} J$$
Work done by centripetal force in revolving a satellite around the earth is
  • Zero
  • Unity
  • Infinity
  • Nothing can be decided
If a body moves along a frictionless horizontal surface its weight:
  • Does work
  • Does not work
  • Work partially
  • None of these
$$kg m^2s^{-2}$$ represents the unit of :
  • kinetic energy only
  • work done only
  • potential energy only
  • all the above
A wound watch spring has ______ energy.
  • Mechanical
  • Kinetic
  • Potential
  • Kinetic and potential
Asha lifts a doll from the floor and places it on a table. If the weight of the doll is known, what else does one need to know in order to calculate the work Asha has done on the doll?
  • the time required
  • the height of the table
  • the power she could deliver
  • cost of the doll or the table
If the speed of a motor car becomes six times, then the kinetic energy becomes
  • 6 times
  • 36 times
  • 12 times
  • 24 times
The flowing water of a river primarily possesses ______ energy.
  • gravitational
  • potential
  • electrical
  • kinetic
When a body moves with a constant speed along a circle, then which of the following is correct : 
  • no force acts on it
  • its velocity remains constant
  • no work is done on it
  • no acceleration is produced in it
Two bodies of equal weight are kept at heights of h and 1.5 h respectively. The ratio of their P.E. will be :
  • 3: 2
  • 2: 3
  • 1: 1
  • none of these
A body rolling down a hill has :
  • K.E. only
  • P.E. only
  • neither K.E. nor P.E.
  • both K.E. and P.E
The kinetic energy of a body is increased by increasing its:
  • Mass
  • Weight
  • Velocity
  • Potential energy
Kilowatt hour (kWh) represents the unit of :
  • power
  • impulse
  • momentum
  • energy
The unit of power is:
  • watt per second
  • joule
  • kilo joule
  • watt
A ball of mass $$200  g$$ falls from a height of $$5  m$$. What is its K.E. when it just reaches the ground ?
  • $$9.8 J$$
  • $$98 J$$
  • $$980 J$$
  • None of these
The number of joules contained in $$1  kWh$$ is
  • $$36 \times {10}^{2}$$
  • $$36 \times {10}^{3}$$
  • $$36 \times {10}^{4}$$
  • $$3.6 \times {10}^{6}$$
An object of mass $$1  kg$$ has a P.E. of $$1  J$$ relative to the ground when it is at a height of
  • $$0.1 m$$
  • $$1 m$$
  • $$9.8 m$$
  • $$32 m$$
A raised hammer possesses :
  • K.E. 
  • P.E.
  • electrical energy
  • sound energy
A body at rest can have:
  • speed
  • energy
  • momentum
  • velocity
Work done upon a body is
  • a vector quantity
  • a scalar quantity
  • always positive
  • always negative
The mass of an object $$P$$ is double the mass of $$Q$$. If both move with the same velocity, then the ratio of K.E. of $$P$$ to $$Q$$ is
  • 1 : 2
  • 2 : 1
  • 1 : 4
  • 4 : 1
Mechanical work done is equal to (symbol have their usual meanings)
  • $$W=\frac { F }{ S } $$
  • $$W=FS$$
  • $$W=F+S$$
  • $$W=F-S$$
A person walks $$100$$ m, holding a suitcase of weight $$100$$ N. The work done by the applied force is ____ J. 
  • $$10000$$
  • $$100$$
  • zero
  • $$5000$$
The product of force and displacement equals:
  • work
  • power
  • momentum
  • none of these
(i) What is the work done by the porter when he climbs up a height of 10 m $$\displaystyle (g\quad = 10\ {ms} ^{-2})$$? 
  • $$5kJ^2$$
  • $$50kJ$$
  • $$100kJ^2$$
  • $$5kJ$$
A force of $$5\ N$$ causes a displacement of $$10\ m$$ in its direction. Calculate the work done by the force.
  • $$15\ J$$
  • $$25\ J$$
  • $$50\ J$$
  • $$200\ J$$
What is the work done by a force of 2 N in displacing a body by 2 m in the direction of the force?
  • $$4J^2$$ 
  • $$6J$$ 
  • $$4J$$ 
  • $$48J$$ 
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