# Work, Energy and Power (KVPY (Kishore Vaigyanik Protsahan Yojana) Stream-SA (Class 11) Physics): Questions 5 - 8 of 25

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## Question number: 5

» Work, Energy and Power » Conservative and Non-Conservative Forces

Appeared in Year: 2014

MCQ▾

### Question

Two positively charged spheres of masses m1, and m2, are suspended from a common point at the ceiling by identical insulating massless strings of length l. Charges on the two spheres are q1 and q2, respectively. At equilibrium both strings make the same angle θ with the vertical. Then

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 6

» Work, Energy and Power » Conservative and Non-Conservative Forces

MCQ▾

### Question

A box, when hung from a spring balance shows a reading of 35 kg inside an evacuated chamber. If the same box is hung from the same spring balance outside an evacuated chamber, the reading on the scale will be,

### Choices

Choice (4) Response

a.

35 kg because the effect of the absence of the atmosphere will be identical on the box and the spring balance

b.

35 kg because the mass of the box remains unchanged

c.

Less than 35 kg because the atmospheric buoyancy force will be present

d.

More than 35 kg because the spring constant is lower in air.

## Question number: 7

» Work, Energy and Power » Power

MCQ▾

### Question

A 250 W motor drivers a pump which lifts 90 liters of water per minute to a height of 4 meters. The efficiency of the motor is nearly (take acceleration due to gravity to be 10 m/s2)

### Choices

Choice (4) Response

a.

28 %

b.

26 %

c.

24 %

d.

22 %

## Question number: 8

» Work, Energy and Power » Power

MCQ▾

### Question

A boy of weight 50 kg climbs up a staircase carrying 15 kg load on his head. The staircase has 35 steps and each step has a height of 15 cm. If he takes 20 seconds to climb, calculate the power developed by him. (g = 9.8 ms-2)

### Choices

Choice (4) Response

a.

167.21

b.

323.3

c.

527.5

d.

95.32

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