Work, Energy and Power Test

Result

Work, Energy and Power Test - 38

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Weekly Quiz Competition

Question 1
4 / -1

A coolie 2.0 m tall raises a load of 75 kg in 25 from the ground to his head and then walks a distance to 40 m in another 25. The power developed by the coolie is ( g = 10 m/s²)

A
0.25 kw

B
0.50 kw

C
0.75 kw

D
1.00 kw

Solution
Question 2
4 / -1

A rubber ball is dropped from a height of 5 m on a planet where the acceleration due to gravity is not known. On bouncing, it rises to 1.8 m. The ball losses its velocity on bouncing by a factor of

A
16/25

B
9/25

C
3/5

D
2/5

Solution
Question 3
4 / -1

Two solid rubber balls P and Q having masses 200 g and 400 g respectively are moving in opposite directions with velocity of P equal to 0.3 m/s. After collision the two balls come to rest, then the velocity of Q is

A
0.15 m/s

B
1.5 m/s

C
–0.15 m/s

D
Zero

Solution
Question 4
4 / -1

A sphere collides with another sphere of identical mass. After collision, the two sphere move. The collision is inelastic. Then the angle between the directions of the two spheres is

A
Different from 90^o

B
90^o

C
0^o

D
45^o
Question 5
4 / -1

If a skater of weight 4 kg has initial speed 40 m/s and 2^nd one of weight 6 kg has 6 m/s. After collision, they have speed (couple) 6 m/s. Then the loss in K.E. is.....

A
48 J

B
zero

C
96 J

D
None of these

Solution
Question 6
4 / -1

A neutron having mass of 1.67 × 10^–27 kg and moving at 10⁸ m/s collides with a deutron at rest and sticks to it. If the mass of the deutron is 3.34 × 10^–27 kg then the speed of the combination is

A
3.33 × 10⁷ m/s

B
3 × 10⁵ m/s

C
33.3 × 10⁷ m/s

D
2.98 × 10⁵ m/s
Question 7
4 / -1

Three identical spherical balls A, B and C are placed on a table as shown in the figure along a straight line. B and C are at rest initially. The ball A hits B head on with a speed of 10 m/s. Then after all collision A and B are brought to rest and C takes off with velocity of...... (elastic collision).

A
20 m/s

B
2.5 m/s

C
10 m/s

D
7.5 m/s
Question 8
4 / -1

A billiard ball moving with a speed of 8 m/s collides with an identical ball originally at rest. If the first ball stops after collision, then the second ball will move forward with a speed of..... (elastic collision)

A
8 m/s

B
4 m/s

C
16 m/s

D
1.0 m/s
Question 9
4 / -1

Four identical balls are lined in a straight grove made on a horizontal frictionless surface as shown. Two similar balls each moving with a velocity v collide elastically with the row of 4 balls from left. What will happen

A
One ball from the right rolls out with a speed 2v and the remaining balls will remain at rest.

B
Two balls from the right roll out speed v each and the remaining balls will remain statinary.

C
All the four balls in the row will roll out with speed v/4 each and the two colliding balls will come to rest.

D
The colliding balls will come to rest and no ball rolls out from right.
Question 10
4 / -1

Assertion : The change in kinetic energy of a particle is equal to the work done on it by the net force.
Reason : Change in kinetic energy of particle is equal to the work done only in case of a system of one particle.

A
If both assertion and reason and the reason is the correct explanation of the Assertion.

B
If both assertion and reason are true but reason is not the correct explanation of the assertion.

C
If the assertion is true but reason is false.

D
If the assertion and reason both are fare.