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Question (41)

QN0026356

A machine does 15000 J work in 50 s. Find power.

(A) 3 W
(B) 30 W
(C) 300 W
(D) 3000 W

Correct Answer: C

Explanation:

Power = 15000 ÷ 50 = 300 W.

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Question (42)

QN0026357

A 2 kW heater operates for 1 second. Energy used is:

(A) 2 J
(B) 20 J
(C) 200 J
(D) 2000 J

Correct Answer: D

Explanation:

Energy = Power × Time = 2000 × 1 = 2000 J.

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Question (43)

QN0026358

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 (44)

QN0026359

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:

1 watt = 1 joule per second.

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Question (45)

QN0026360

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 (46)

QN0026361

A screw is actually a modified:

(A) Pulley
(B) Inclined plane
(C) Lever
(D) Wedge

Correct Answer: B

Explanation:

Screw is an inclined plane wrapped around a cylinder.

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Question (47)

QN0026362

A machine has load 600 N and effort 150 N. Its mechanical advantage is:

(A) 2
(B) 3
(C) 4
(D) 5

Correct Answer: C

Explanation:

MA = Load ÷ Effort = 600 ÷ 150 = 4.

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Question (48)

QN0026363

Which simple machine is present in a door knob?

(A) Pulley
(B) Lever
(C) Wheel and axle
(D) Inclined plane

Correct Answer: C

Explanation:

Door knob works on wheel and axle principle.

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Question (49)

QN0026364

The efficiency of a machine is always:

(A) Greater than 100%
(B) Equal to 100%
(C) Less than or equal to 100%
(D) Infinite

Correct Answer: C

Explanation:

Efficiency cannot exceed 100%.

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Question (50)

QN0026365

A machine has load 900 N and mechanical advantage 3. Effort applied is:

(A) 100 N
(B) 200 N
(C) 300 N
(D) 600 N

Correct Answer: C

Explanation:

Effort = Load ÷ MA = 900 ÷ 3 = 300 N.

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Question (41)

A machine does 15000 J work in 50 s. Find power.

Explanation:

Link:

Question (42)

A 2 kW heater operates for 1 second. Energy used is:

Explanation:

Link:

Question (43)

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

Explanation:

Link:

Question (44)

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

Explanation:

Link:

Question (45)

Which quantity depends on both work done and time taken?

Explanation:

Link:

Question (46)

A screw is actually a modified:

Explanation:

Link:

Question (47)

A machine has load 600 N and effort 150 N. Its mechanical advantage is:

Explanation:

Link:

Question (48)

Which simple machine is present in a door knob?

Explanation:

Link:

Question (49)

The efficiency of a machine is always:

Explanation:

Link:

Question (50)

A machine has load 900 N and mechanical advantage 3. Effort applied is:

Explanation:

Link:

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