MCQ Work Energy and Power for ICSE Physics Class-10

Answer (a) 5500 kg

Potential energy = mgh

Efficiency = 40 %

Useful work done = 40 % of potential energy

= 40 / 100 (mgh)

= 0.4 (m × 10 × 50)

= 200 m

Power = work done per second

1MW = 200 × mass of water flowing each second

1 × 10⁶W = 200 × mass of water flowing each second

mass of water flowing each second = (1 × 10⁶) / 200

= 5000 kg

Question 8  A boy drags a load ‘L’ along horizontal plane AB by applying a force F. The boy does

(a) no work
(b) some positive work
(c.) negative work
(d) none of these

Answer (b) some positive work

Question 9  The SI unit of work is joule. It is expressed in terms of mass, length and time as

(a) kg m²s^-3
(b) kg m²s^-2
(c) kg2 m²s^-2
(d) kg m²s^-2

Answer (a) kg m²s^-3

Question 10 The SI unit of power is watt. It is expressed in terms of mass, length and time as:

(a) kg m²s^-3
(b) kg ms^-3
(c) kg2 m²s^-2
(d) kg ms^-2

Answer (a) kg m²s^-3

Question 11 A stone resting on the roof ofa building has

(a) potential energy
(b) gravitational energy
(c) kinetic energy
(d) none of these

Answer (a) potential energy

Question 12  A falling raindrop has :

(a) only kinetic energy
(b) only potential energy
(c) both kinetic and potential energy
(d) none of these

Answer (c) both kinetic and potential energy

Question 13 One horse power is equal to :

(a) 764 W
(b) 746 W
(c) 700 W
(d) 1000 W

Answer (b) 746 W

Question 14  One electron volt is equal to :

(a) 6 x 10-¹⁷ J
(b) 6.1 x 10-¹⁹ J
(c) 6 x 10-¹⁹ J 
(d) 1.6 x 10-¹⁰ J

Answer (c) 6 x 10-¹⁹ J

Question 15 Kilowatt hour is the commercial unit of:

(a) electric power
(b) electric energy
(c) electric force
(d) none of these

Answer (b) electric energy

Question 16 Power is the product of:

(a) force and velocity
(b) force and displacement
(c) force and acceleration
(d) force and time

Answer (a) force and velocity

Question 17  An aeroplane is flying at an altitude of 10,000 m at a speed of 300 km/hour. The aeroplane at this height has :

(a) only kinetic energy
(b) only potential energy
(c) both kinetic and potential energy
(d) zero kinetic and potential energy

Answer (c) both kinetic and potential energy

Question 18  Kilocalorie is the amount of heat required to raise the temperature of:

(a) one gram of water through 1°C
(b) 1 kg of water through 100°
(c)  one kg of water through 1°C
(d) 1 kg of water through 10°C Arts.

Answer (c)  one kg of water through 1°C

Question 19  When a flash light is switched on the electric energy

(a) directly changes to light energy
(b) first changes to light energy and then to heat energy
(c) first changes to heat energy and then to light energy
(d) none of above

Answer (b) first changes to light energy and then to heat energy

Question 20 A pendulum is swinging freely. The bob ofpendulum has:

(a) maximum K.E. at its extreme positions
(b) minimum K.E. at its mean position
(c) maximum K.E. at its mean position
(d) both (b) and (c)

Answer (c) maximum K.E. at its mean position

Question 21 A pendulum is oscillating freely. Its bob has :

(a) only kinetic energy
(b) maximum kinetic energy at extreme position
(c) maximum potential energy at its mean position
(d) a constant energy which is the sum of potential and kinetic energy

Answer (d) a constant energy which is the sum of potential and kinetic energy 

Question 22 A ball of mass m is dropped from height ‘h ’.

(a) Potential energy of the ball at ground level is mgh.
(b) Potential energy of the ball at height h is mgh.
(c) kinetic energy of the ball at ground level is mgh
(d) both (b) and (c)

Answer (b) Potential energy of the ball at height h is mgh.

Question 23  A work of 1000 J is done on a body in 4 s, such that a displacement of 20 m is caused. Calculate
(a) force (b) power

(a) 50 N and 250 w
(b) 55 N and 250 w
(c) 50 N and 260 w
(d) 40 N and 350 w

Answer (a) 50 N and 250 w

Question 24  What force must be applied to a body through a distance of 10 m, such that it does a work of 4000 J. If the mass of the body is 20 kg, what is the acceleration of the body ?

(a) 25 ms^-2
(b)  20 ms^-2
(c)  28 ms^-2
(d)  30 ms^-2

Answer (b)  20 ms^-2

Question 25  An engine of power 200 W, operates for 4 s. Find the work done by the engine. If the force developed by the engine is 100 N calculate the maximum displacement caused.

(a) 8 m
(b) 4 m
(c) 16 m
(d)  12 m

Answer (a) 8 m 

Question 26  An electric pump is 60% efficient and is rated 2 HP. Calculate the maximum amount of water it can lift through a height of 5 m in 40 s. [Take g = 10 ms^-2 and 1 HP = 750 W]

(a) 750 kg
(b) 620 kg

(c) 720 kg
(d) 650 kg

Answer (c) 720 kg

Power of lift pump = 2 HP

Question 27  Calculate the time for which a motor pump of 10 HP and efficiency 80% must be switched on, so as to pump 20 m³ of water through a vertical height of 20 m.[Density of water = 1000 kg m³; g = 10 ms^-2; 1 HP = 750 W] 

(a) 658.67 sec
(b) 666.67 sec

(c) 766.77 sec
(d) 886.67 sec

Answer (b) 666.67 sec

Question 28  In a hydroelectric power station, 1000 kg of water is allowed to drop a height of 100 in in ¡ s. If the conversion of potential energy to electric energy is 60%, calculate the power output.

(a) 8 x 10³ w
(b) 12 x 10⁵ w

(c) 6 x 10⁸ w
(d) 6 x 10⁵ w

Answer (d) 6 x 10⁵ w

Question 29 A compressed spring is held near a small toy car of mass 0.15 kg. On the release of the spring, the toy car moves forward with a velocity of 10 ms’. Find the potential energy of the spring.

(a) 7.5 j
(b)  7.8 j

(c)  8.5 j
(d)  6.5 j

Answer (a) 7.5 j

mass of car m = 0.15 kg
velocity y = 10 ms^-1

kinetic energy K.E. = 1/2 mv²

1/2 x(15/100) x 10 x 10  = 7.5 j

Question 30  A catapult throws a stone of mass 0.10 kg with a velocity of 30 ms^-1. If 25% of the RE. of the elastic band is wasted during transmission, find the magnitude of the potential energy.

(a) 120 j
(b) 50 j

(c) 160 j
(d) 60 j

Answer (d) 60 j

Let pot. energy = RE.
P.E. wasted = 25%
P.E. used 100—25 = 75%

Question 31 A bullet of mass 0.2 kg, moving with a velocity of 200 ms^-1 , strikes a stationary wooden target of mass 5 kg. If all the energy is transferred to the wooden target, calculate the velocity with which the target towards direction.

(a) 20 ms^-1
(b) 80 ms^-1

(c) 40 ms^-1
(d) 45 ms^-1

Answer (c) 40 ms^-1

Let the other body (B) moves with kinetic energy of bullet = K.E. of wooden target (B)

Question 32 A scooter develops a power of 1 HP while running at 36 km hr^-1. Calculate the force generated by its engine.

(a) 40 N(1/2)
(b) 75 N(1/2)

(c) 150 N(1/2)
(d) 72 N(1/2)

Answer (b) 75 N(1/2)

Question 33  The heart of a normal person beats 72 times in a minute and does a work of 1 joule per beat. What is power of the heart ?

(a) 1.2 w
(b) 3.6 w

(c) 2.4 w
(d) 1.5 w

Answer (a) 1.2 w

Work done per beat = 1 J
work done for 72 beats = 72 J

Power = (workdone/60 s) = 72/60 = 1.2 w

Question 34  An accelerated electron has energy of 9.6 x 10^-18 J. Express the energy in electron volts (eV)

(a) 120 eV
(b) 240 eV

(c) 60 eV
(d) 150 eV

Answer (c) 60 eV

Question 35  Calculate the kinetic energy of a body of mass 5 kg momentum 50 kg ms^-1

(a) 550 j
(b) 500 j

(c) 200 j
(d) 250 j

Answer (d) 250 j

Mass m = 5 kg
move (Questions from ICSE Examination Papers) (Questions from ICSE Examination Papers) mentum p = mv = 50 kg ms^-1

5 V = 50  

v = 50/5

= 10 ms^-1

K.E. = 1/2 x 5 x 10 x 10 = 250 j

–: End of ICSE Physics Class-10 Machine MCQ Type Questions :-

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