Work, Energy and Power Test

Result

Work, Energy and Power Test - 14

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Weekly Quiz Competition

Question 1
4 / -1

The kinetic energy of a body becomes four times its initial value. The new momentum will be

A
same as the initial value

B
twice the initial value

C
thrice the initial value

D
half of its initial value

Solution
Question 2
4 / -1

The centripetal acceleration of a particle varies inversely with the square of the radius r of the circular path. The kinetic energy of this particle varies directly as

A
r

B
r²

C
r^-2

D
r^-1

Solution
Question 3
4 / -1

A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x is proportional to

A
x²

B
e^x

C
x

D

Solution
Question 4
4 / -1

When a spring is extended by 2 cm energy stored is 100 J. When extended by further 4 cm, the energy increases by

A
400 J

B
300 J

C
200 J

D
100 J

Solution
Question 5
4 / -1

A block of mass m = 25 kg sliding on a smooth horizontal surface with a velocity v = 3 ms^-1 meets the spring of spring constant k =100 Nm^-1 fixed at one end as shown in figure. The maximum compression of the spring and velocity of block as it returns to the original position respectively are

A
1.5 m, -3 ms^-1

B
1.5 m, 0.01 ms^-1

C
1.0 m , 3 ms^-1

D
0.5 m ,2 ms^-1

Solution
Question 6
4 / -1

Two springs of spring constants 1500 Nm^-1 and 3000 Nm^-1 respectively are stretched with the same force. They will have potential energy in ratio

A
1 : 2

B
2 : 1

C
1 : 4

D
4 : 1

Solution
Question 7
4 / -1

A ball of mass 2 kg moving with velocity 3 ms^-1, collides with spring of natural length 2m and force constant 144 Nm^-1. What will be length of compressed spring?

A
2 m

B
1.5 m

C
1 m

D
0.5 m

Solution
Question 8
4 / -1

A steel ball of mass 5 g is thrown downward with velocity 10 ms^-1 from height 19.5 m. it penetrates sand by 50 cm. The change in mechanical energy will be (take, g =10ms^-2 )

A
1 J

B
1.25 J

C
1.5 J

D
1.75 J

Solution
Question 9
4 / -1

To the free end of spring hanging from a rigid support, a block of mass m is hung and slowly allowed to come to its equilibrium position. Then stretching in the spring is d. If the same block is attached to the same spring and allowed to fall suddenly, the amount of stretching is (force constant, k)

A

B
2d

C

D
4d

Solution
Question 10
4 / -1

The upper half of an inclined plane with inclination ϕ is perfectly smooth, while the lower half is rough. A body starting from rest at the top will again come to rest at the bottom, if the coefficient of friction for the lower half is given by

A
2 sin ϕ

B
2 cos ϕ

C
2 tan ϕ

D
tan ϕ

Solution