Work, Energy and Power Test

Result

Work, Energy and Power Test - 21

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Weekly Quiz Competition

Question 1
4 / -1

A rock weighing 50 N falls from a height of 10 m and sinks 0.5 m into the ground. From energy consideration, the average force f between the rock and the ground as the rock sinks is :

A
105 N

B
10.50 N

C
1050 N

D
1360 N

Solution
Question 2
4 / -1

The vessels A and B of equal volume and weight are immersed in water to depth h. The vessel A has an opening at the bottom through which water can enter. If the work done in immersing A and B are W_A and W_B respectively, then:

A
W_A = W_B

B
W_A < W_B

C
W_A > W_B

D
Question 3
4 / -1

A block of mass 0.5 kg has an initial velocity of 10m/s down an inclined plane of angle 30⁰, the coefficient of friction between the block and the inclined surface is 0.2. The velocity of the block after it travels a distance of 10 m is

A
17 m/s

B
13 m/s

C
24 m/s

D
8 m/s

Solution
Question 4
4 / -1

An object of mass m is tied to a string of length l and a variable horizontal force is applied on it , which starts at zero and gradually increases (it is pulled extremely slowly so that quilibrium exists at all times) until the string makes an angle Ө with the vertical. Work done by the force F is

A
mgl (1 ‒ sin θ)

B
mgl

C
mgl (1 ‒ cos θ)

D
mgl (1 ‒ tan θ)
Question 5
4 / -1

A stone of mass m kg is whirled in a vertical circle of radius 20 cm .The difference of the kinetic energies at the lowest and the topmost position is :

A
4 mg joule

B
0.4 mg joule

C
40 mg joule

D
None of these

Solution
Question 6
4 / -1

A ball is allowed to fall down with initial speed v from a height of 10 m. It loses 50 % kinetic energy after striking the floor. It reaches to the same height after collision.What is the value of v ?

A
28 m/ s

B
7 m/s

C
14 m/s

D
it is never possible

Solution
Question 7
4 / -1

A mass of 2 kg rests on an inclined plane of gradient 1 in 8 as shown in fig. The work done in sliding it from the lowest point of the incline to the highest point, if the coefficient of friction is 0.2, is :

A
192 J

B
19.2 J

C
48 J

D
52 J

Solution
Question 8
4 / -1

A small body is projected in a direction inclined at 45º to the horizontal with kinetic energy K. At the top of its flight, its kinetic energy will be:

A
Zero

B
K/2

C
K/4

D

Solution
Question 9
4 / -1

Two springs have their force constants k₁ and k₂. These are extended through the same distance x. If their elastic energies are E₁ and E₂, then E₁ : E₂ will be :

A

B

C

D

Solution
Question 10
4 / -1

A compressor A compresses one litre of air from a pressure of 1atmosphere to a pressure of 3 atmosphere and does work W_A . But compressor B compresses one litre of water from a pressure of one atmosphere to three atmosphere and does work W_B, then

A
W_A = W_B

B
W_A < W_B

C

D
W_A > W_B

Solution