CBSE Questions for Class 9 Physics Work And Energy Quiz 4 - MCQExams.com

According to the law of conservation of energy, total energy is
  • Increasing
  • Decreasing
  • Constant
  • None of these
Which of the following physical quantities is different from others?
  • Work
  • Kinetic energy
  • Force
  • Potential energy
If work done by the net force is zero, work done by the individual forces needs to be zero.
  • True
  • False
A body is acted upon by a force that is proportional to the distance covered. If the distance covered is denoted by x, then work done by the force will be proportional to :
  • $$x$$
  • $$x^2$$
  • $$\displaystyle x^{\dfrac{3}{2}}$$
  • $$x^4$$
One megawatt is .................... times that of one kilowatt.
  • $$1000$$
  • $$19600$$
  • $$100000$$
  • $$0.001$$
If force and displacement of the particle (in direction of force) are doubled, Work should be :
  • Doubled
  • Quadrupled
  • Halved
  • Reduced by $$\displaystyle \frac{1}{4} times$$
When a force retards the motion of a body, the work done is :
  • Zero
  • Negative
  • Positive
  • Positive or negative depending upon the magnitude of force and displacement
The work done in holding $$15\ kg$$ suitcase while waiting for a bus for $$45$$ minutes is :
  • $$675\ J$$
  • $$40500\ J$$
  • $$4500\ J$$
  • $$Zero$$
If $$1 \ N$$ of the force displaces the body through $$1 \ m$$ in the direction of force, then the work done is said to be ______.
  • $$1 \ J$$
  • $$1\ N-m$$
  • $$1 \ N-cm$$
  • none of the above
Choose the correct option.
  • $$kW=$$ unit of power and $$kWh =$$ unit of energy.
  • $$kW=$$unit of energy and $$kWh =$$ unit of power.
  • $$kW$$ and $$kWh$$ are both of unit of energy.
  • $$kW$$ and $$kWh$$ are both of unit of power.
How much work is done by a force 50 N moving an object through a distance 10 m in the direction of force ?
  • $$5 \ J$$
  • $$500\  J$$
  • $$0.5\  J$$
  • $$0\  J$$
A boy carrying a box on his head is walking on a level road from one place to another on a straight road is doing no work against gravity.
  • True
  • False
What will be the potential energy of a body of mass 5 kg kept at a height of 10 m ?
  • 50 J
  • 0.5 J
  • 500 J
  • 25 J
A fish swimming in water possess mechanical energy.
  • True
  • False
The work done by a force on a body will be positive if the body -
  • Moves perpendicular to the direction of applied force
  • Does not move
  • Moves along the direction of applied force
  • Moves opposite to the direction of applied force
An electric toaster draws $$8\ A$$ current in a $$220\ V$$ circuit. It is used for $$2\ hr$$. What is the cost of operating the toaster if the cost of electrical energy is $$Rs.\ 4.5 / kWh$$?
  • $$Rs.\ 9.50$$
  • $$Rs.\ 25.50$$
  • $$Rs.\ 14.84$$
  • $$Rs.\ 15.84$$
In our household applications, commercial unit of electricity is used. One unit is equal to:
  • $$1\ kW$$
  • $$1\ kWh$$
  • $$1\ kW/h$$
  • $$1\ Wh$$
A machine raises a load of $$750N$$ through a height of $$16m$$ in $$5s$$. Calculate work done by machine:
  • $$12000 kJ$$
  • $$12 kJ$$
  • $$1200 J$$
  • $$120 kJ$$
A pump is used to lift $$500\ kg$$ of water from a depth of $$80\ m$$ in $$10\ s$$.
(Take $$g=10\ ms^{-2}$$). Calculate the work done by the pump.
  • $$16 \times 10^5J$$
  • $$4\times 10^5J$$
  • $$4\times 10^8J$$
  • $$2\times 10^5J$$
A body when acted upon by a force of $$10\ kgf$$, gets displaced by $$0.5\ m$$. Calculate the work done by the force, when the displacement is in the direction of force.
  • $$5 J$$
  • $$500 J$$
  • $$0.5 J$$
  • $$50J$$
A boy carrying a box on his head is walking on a level road from one place to another. The work done by him against the gravitational force is zero. This statement is :
  • correct
  • incorrect
  • partly correct
  • insufficient data
A man spends $$6.4 \ kJ$$ energy in displacing a body by $$64 \ m$$ in the direction in which he applies force, in $$2.5 \ s$$. 
Calculate the force applied.
  • $$1N$$
  • $$10N$$
  • $$0.1N$$
  • $$100N$$
Name the type of energy (kinetic energy $$K$$ or potential energy $$U$$) possessed in the following case.
The bob of a simple pendulum at its extreme position.
  • $$K$$
  • $$U$$
  • $$K$$ and $$U$$
  • No energy
A man raises a box of mass $$50 \ kg$$ to a height of $$2 \ m$$ in $$2 \ minutes$$, while another man raises the same box to the same height in $$5 \ minutes$$. What is the ratio of work done by them ?
  • $$1 : 1$$
  • $$2 : 1$$
  • $$1 : 2$$
  • $$4 : 1$$
Before a rubber ball bounces off from the floor, the ball is in contact with the floor for a fraction of second. Which of the following statements are correct?
  • Conservation of energy is not valid during this period
  • Conservation of energy is valid during this period
  • Only the kinetic energy is conserved
  • Only the potential energy is conserved
An electric heater of power $$3 \ kW$$ is used for $$10 \ h$$. How much energy does it consume? Express your answer in joule.
  • $$1.08\times 10^5$$
  •  $$1.08\times 10^8$$
  • $$1.08\times 10^7$$
  • $$1.08\times 10^3$$
A body is moved in a direction opposite to the direction of force acting on it. Work is done is:
  • against the force
  • zero
  • along the force
  • none of these
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
  • $$Force \times Displacement$$
  • $$Force \times velocity$$
  • $$Force \times acceleration$$
  • $$Force \times Distance$$
Name the type of energy (kinetic energy $$K$$ or potential energy $$U$$) possessed in the following case.
A piece of stone placed on the roof.
  • $$U$$
  • $$K$$
  • $$U$$ and $$K$$
  • No energy
State whether the given statement is True or False :
The energy of an object that is due to the object's motion is called kinetic energy.
  • True
  • False
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