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Question (31)

QN006392

A machine does 400 J work each second. Its power is:

(A) 40 W
(B) 400 W
(C) 4000 W
(D) 4 W

Correct Answer: B

Explanation:

400 J/s = 400 W

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Question (32)

QN006393

A labourer develops 250 W power. Work done in 4 s is:

(A) 62.5 J
(B) 1000 J
(C) 250 J
(D) 254 J

Correct Answer: B

Explanation:

Work = 250 × 4 = 1000 J

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Question (33)

QN006394

Greater power implies:

(A) Greater time taken
(B) Faster rate of energy transfer
(C) Smaller work done always
(D) No energy conversion

Correct Answer: B

Explanation:

Power is rate of energy transfer.

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Question (34)

QN006395

A machine performs 18000 J work in 1 minute. Power developed is:

(A) 18 W
(B) 180 W
(C) 300 W
(D) 1080000 W

Correct Answer: C

Explanation:

Time = 60 s; Power = 18000 ÷ 60 = 300 W

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Question (35)

QN006396

The power of an engine indicates:

(A) Its weight
(B) Its colour
(C) Rate of doing work
(D) Its temperature

Correct Answer: C

Explanation:

Power shows how fast work is done.

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Question (36)

QN006397

An electric motor of 1500 W works for 2 s. Work done equals:

(A) 3000 J
(B) 750 J
(C) 1500 J
(D) 500 J

Correct Answer: A

Explanation:

Work = 1500 × 2 = 3000 J

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Question (37)

QN006398

Which statement is correct about power?

(A) It is always constant
(B) It is scalar quantity
(C) It has no unit
(D) It depends only on mass

Correct Answer: B

Explanation:

Power is a scalar quantity.

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Question (38)

QN006399

A machine does 960 J work in 12 s. Power is:

(A) 8 W
(B) 80 W
(C) 11520 W
(D) 960 W

Correct Answer: B

Explanation:

Power = 960 ÷ 12 = 80 W

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Question (39)

QN006400

A bulb rated 60 W converts electrical energy into light and heat at the rate of:

(A) 6 J/s
(B) 60 J/s
(C) 600 J/s
(D) 3600 J/s

Correct Answer: B

Explanation:

60 W = 60 J/s

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Question (40)

QN006401

Which quantity depends on both work done and time taken?

(A) Momentum
(B) Velocity
(C) Power
(D) Acceleration

Correct Answer: C

Explanation:

Power depends on work and time.

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Question (31)

A machine does 400 J work each second. Its power is:

Explanation:

Link:

Question (32)

A labourer develops 250 W power. Work done in 4 s is:

Explanation:

Link:

Question (33)

Greater power implies:

Explanation:

Link:

Question (34)

A machine performs 18000 J work in 1 minute. Power developed is:

Explanation:

Link:

Question (35)

The power of an engine indicates:

Explanation:

Link:

Question (36)

An electric motor of 1500 W works for 2 s. Work done equals:

Explanation:

Link:

Question (37)

Which statement is correct about power?

Explanation:

Link:

Question (38)

A machine does 960 J work in 12 s. Power is:

Explanation:

Link:

Question (39)

A bulb rated 60 W converts electrical energy into light and heat at the rate of:

Explanation:

Link:

Question (40)

Which quantity depends on both work done and time taken?

Explanation:

Link:

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