CBSE Questions for Class 9 Physics Work And Energy Quiz 6 - MCQExams.com

An overhead tank having some water possesses .......... energy.
  • Kinetic
  • Potential
  • Thermal
  • Electrical
Potential energy is directly proportional to:
  • velocity of the body
  • speed of the body
  • height of the body from the surface
  • shape of the body
Which of the following does has kinetic energy ?
  • An inflated balloon
  • Water in a flowing river
  • A fruit on the tree
  • A stationary plane
Which of the following possesses kinetic energy?
  • A fallen tree
  • Running athlete
  • Wound watch spring
  • Boy standing on the road
A box of mass $$1\ kg$$ is pulled on a horizontal plane of length $$1\ m$$  by a force of $$8\ N$$  then it is raised vertically to a height of $$2$$ m, the net work done is:
  • 28 J
  • 8 J
  • 18 J
  • none of the above
Energy is the capacity to do work.
  • True
  • False
A rigid body of mass $$m$$ kg is lifted uniformly by a man to a height of one metre in $$30$$ sec. Another man lifts the same mass to the same height in $$60$$ sec. The work done on the body against gravitation in both the cases are in ratio:
  • 1 : 2
  • 1 : 1
  • 2 : 1
  • 4 : 1
The law of conservation of energy implies that the:
  • Total mechanical energy is conserved
  • Total kinetic energy is conserved
  • Total potential energy is conserved
  • Sum of all kinds of energies is conserved
In which one of the following cases is work done the maximum ?
  • Mohan pushes against a wall for $$30 \ minutes$$
  • Mohan pushes a bicycle which moves through a distance of $$1.5 \ m$$
  • Mohan pushes a truck which does not move at all
  • Mohan stands in the centre of his room
What is work done in holding a body of mass $$20\ kg$$ at a height of $$2\ m$$ above the ground? $$(g = 10\ m/s^2)$$
  • $$40\ J$$
  • $$400\ J$$
  • $$10\ J$$
  • Zero
Which one of the following possesses kinetic energy?
  • A moving car
  • A compressed spring
  • Water stored in the reservoir of a dam
  • A car parked in the garage
Work done by static friction force when a person starts running is .......... .
  • equal to the weight of the person
  • zero
  • infinite
  • cannot be calculated
A vehicle travelling at $$30 \ m/s$$ stops at a distance of $$50 \ m$$ decelerating uniformly. A force of $$9000 \ N$$ is exerted on it by the brakes. What is the work done by the brakes?
  • $$4.5 \times 10^4 \ J$$ 
  • $$2.7 \times 10^5 \ J$$ 
  •  $$4.5 \times 10^5 \ J$$ 
  • $$2.7 \times  10^4 \ J$$ 
How fast should a girl of 40 kg run so that her kinetic energy is 320J?
  • 64 m/s
  • 8 m/s
  • 16 m/s
  • 4 m/s
Energy conservation law says that:
  • Energy can't be destroyed but can be produced.
  • Neither energy can be produced nor can be destroyed.
  • Energy can't be produced but can be destroyed.
  • Energy can be produced and can be destoyed
A body at rest have:
  • Energy
  • Momentum
  • Speed
  • Velocity
The velocity of a bus, moving on a smooth road, is increased from 8 m/s to 32 m/s in 120s. During this process, the potential energy of the bus
  • Does not change
  • Becomes twice that of initial potential energy
  • Becomes four times that of initial potential energy
  • Becomes sixteen times that of initial potential energy
Two bodies P and Q of equal masses are kept at heights $$x$$ and $$4x$$ respectively. What will be the ratio of their potential energies?
  • $$1:8$$
  • $$4:1$$
  • $$1:4$$
  • $$8:1$$
An object of mass 500 g falls from a height of 2m. If $${g = 9.8 m/s^2}$$, what is its kinetic energy just before touching the ground?
  • Zero
  • 19.6 J
  • 9.8 J
  • 9800 J
A stone is projected vertically up to reach maximum height $$h$$. The ratio of its kinetic to potential energies at a height $$\cfrac{4h}{5}$$ will be
  • $$5:4$$
  • $$4:5$$
  • $$1:4$$
  • $$4:1$$
What is the mass of a man if he does $$3600\ J$$ of work in climbing a tree $$6\ m$$ tall? $$({g = 10 m/s^2})$$
  • $$70\ kg$$
  • $$60\ kg$$
  • $$85\ kg$$
  • $$52\ kg$$
When a stone falls freely towards the earth, its total energy ?
  • First decreases and then becomes zero
  • Remains constant
  • Increases
  • Decreases
A car is being driven at a constant speed of $$5\ m/s$$  by a force of $${3\times 10^8}\ N$$. It takes $$2$$ minutes to reach its destination. What is the work done?
  • $${15\times 10^8\ J}$$
  • $${18\times 10^{10}\ J}$$
  • $${6\times 10^{10}\ J}$$
  • $${10\times 10^8 \ J}$$
The velocity of a ball goes on decreasing when it is thrown vertically upwards. When its velocity becomes zero, its potential energy becomes
  • Minimum
  • Maximum
  • Zero
  • 9.8 J
A car is moving at $$100\ km/h$$. If the mass of the car is $$950\ kg$$, Its kinetic energy is:
  • $$367\ MJ$$
  • $$0.367\ MJ$$
  • $$3.67\ MJ$$
  • $$3.67\ J$$
A girl weighing 50 kg makes a high jump of 1.2 m.What is her kinetic energy at the highest point? $${(g= 10 ms^{-2}}$$)
  • 6000 J
  • 600 J
  • 60 J
  • Zero
Which one of the following possesses both kinetic and potential energies?
  • A man walking on the road
  • A man climbing a hill
  • A man lying on his bed
  • A man running in the garden.
A body is under the action of two equal and opposite forces, each of 10 N. The body is displaced by 5 m.The work done is
  • +50J
  • -50J
  • 100J
  • Zero
The spring of the winding knob of a watch has
  • mechanical energy
  • only kinetic energy
  • only potential energy
  • kinetic or potential energy
The energy possessed by wind is
  • kinetic energy
  • potential energy
  • thermal energy
  • sound energy
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