# Multiple choice question for engineering

## Set 1

1. At which temperature, the centigrade and Fahrenheit scales are equally?

a) 40°

b) -40°

c) 37°

d) -80°

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2. The volume of a gas at 20°C is 100cm^{3} at normal pressure. If it is heated to 100°C, its volume becomes 125cm^{3} at the same pressure, then volume coefficients of the gas (at normal pressure) is

a) 0.0033/°C

b) 0.0025/°C

c) 0.0030/°C

d) 0.0021/°C

### View Answer

_{t}=V

_{0}(1+γt) V

_{100}/V

_{20}=(1+100

_{γ})/(1+20

_{γ})=125/100=3/4 γ=1/300=0.0033/°C

3. Density of substance at 0°C is g/cc and 100°C, its density is 9.7g/cc. The coefficient of linear expansion of the substance is

a) 10^{-1}

b) 10^{-2}

c) 10^{-3}

d) 10^{-4}

### View Answer

_{0}-ρ

_{t})/(ρ

_{0}×t)=(10-9.7)/(10×100)=3×10

^{-4}α=γ/3=10

^{-4}°C

^{-1}

4. The coefficient of volumetric expansion of mercury is 18×10^{-5}/°C. The thermometer bulb has a volume of 10^{-6} m^{3} and cross-section of the stem is 0.002cm^{2}. Assuming that bulb is filled with mercury at 0°C, the increase in length of the mercury column at 100°C will be

a) 9cm

b) 9mm

c) 18cm

d) 18mm

### View Answer

^{-5}×10

^{-6}×100)/(0.002×10

^{-4}) m h=9×10

^{-2}m h=9cm

5. Amount of heat required to raise the temperature of a body through 1K is called

a) Specific heat

b) Thermal capacity

c) Water equivalent

d) Entropy

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6. If the temperature of a rod is increased by 10°C, its length increases by 1%. What is the percentage change in volume of the body of the same material for 10°C increase in temperature?

a) 9%

b) 1%

c) 5%

d) 3%

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7. In order that the heat flows from one part of a solid to another part, what is required?

a) Uniform density

b) Temperature gradient

c) Density gradient

d) Uniform temperature

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8. A body A of mass 0.5kg and specific heat 0.85 is at a temperature of 60°C. Another body B of mass 0.3kg and specific heat 0.9 is at a temperature of 90°C. When they are connected to a conducting rod, heat will flow from

a) A to B

b) Heat can’t flow

c) B to A

d) First A to B and then B to A

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9. Two rods having thermal conductivity in the ratio of 5:3 having equal lengths and equal cross-sectional area are joined end to end. If the temperature of the free end of the first rod is 100°C and free end of the second rod is 20°C, then the temperature of the junction is

a) 50°C

b) 70°C

c) 60°C

d) 90°C

### View Answer

_{1}/t=Q

_{2}/t (K

_{1}A(100-T))/d=(K

_{2}A(T-T

_{2}))/d 5(100-T)=3(T-20) 8T=560 or T=70°C

10. Mud houses are cooler in summer and warmer in winter because

a) Mud is a good conductor of heat

b) Mud is a superconductor of heat

c) Mud is a bad conductor of heat

d) Mud can adapt according to temperature

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11. A perfectly black body is one whose

a) Absorptive power is 1

b) Absorptive power is 0

c) Emissive power is 1

d) Absorptive power is 0.5

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12. A black body radiates energy at the rate of 1×10^{5} J/(sm)^{2} at a temperature of 227°C. The temperature to which it must be heated so that it radiates energy at the rate of 1×10^{9} J/(sm)^{2}

a) 5000 K

b) 5000°C

c) 500 K

d) 500°C

### View Answer

_{2}=(E

_{2}/E

_{1})

^{(1/4)}T

_{1}=10×500=5000K

13. A black body at 200 K is found to emit maximum energy at a wavelength 14μm. When its temperature is raised to 1000K, then wavelength at which maximum energy emitted it

a) 14mm

b) 7μm

c) 2.8μm

d) 28mm

### View Answer

^{‘}T

^{‘}=2.8μm

14. The triple point of water is

a) 273.16°C

b) 273.16K

c) 273.16°F

d) 0.15K

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15. During constant temperature, we feel colder on the day when the humidity is

a) 85%

b) 40%

c) 60%

d) 25%

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## Set 2

1. A gun fires a bullet of mass 50g with a velocity of 30m/s. Because of this, the gun is pushed back with a velocity of 1m/s. The mass of the gun is

a) 5.5kg

b) 3.5lg

c) 1.5kg

d) 0.5kg

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2. Rocket engines lift a rocket from the earth surface, because hot gases with high velocity

a) Push against the air

b) Push against the earth

c) React against the rocket and push it up

d) Heat up the air which lifts the rocket

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3. The motion of a rocket is based on the principle of conservation of

a) Linear momentum

b) Angular momentum

c) Kinetic energy

d) Mass

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4. A bullet is fired from the rifle. If the rifle recoils freely, then the kinetic energy of the rifle is

a) Less than the kinetic energy of the bullet

b) More than the kinetic energy of the bullet

c) Same as the kinetic energy of the bullet

d) Equal or less than the kinetic energy of the bullet

### View Answer

_{r}= 1/2MV

^{2}= 1/2M(m

^{2}v

^{2)}/M

^{2}K

_{r}= m/M K

_{b}As m is lesser than M, K

_{r}is lesser than K

_{b}‘=m(g-a) is lesser than W(=mg)

6. A person with a spring balance with a body hanging from it goes up in an aeroplane, then the reading of the weight of the body as indicated by the spring balance, will

a) Go on increasing

b) Go on decreasing

c) First increases and then decreases

d) Remains the same

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7. Assertion: On a rainy day, it is difficult to drive at high speed. [Reason:] The value of coefficient of friction is lowered due to wetting of the surface

a) If both assertion and reason are true and reason is the correct explanation of the assertion

b) If both assertion and reason are true but reason is not correct explanation of the assertion

c) If assertion is true, but reason is false

d) If both assertion and reason are false

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8. A monkey of mass 20 kg is holding a vertical rope. The rope will not break when a mass of 25 kg is suspended from it but will break if the mass exceeds 25kg. What is the minimum acceleration with which the monkey can climb up along the rope? (g= 10m/s^{2})

a) 5m/s^{2}

b) 10m/s^{2}

c) 25m/s^{2}

d) 2.5m/s^{2}

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^{2}

9. A block has been placed on an inclined plane with the slope angle θ, block slides down the plant at constant speed. The coefficient of kinetic energy is equal to

a) sinθ

b) cosθ

c) g

d) tanθ

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10. A man is standing on a spring platform. Reading of spring balance is 60kg wt. If man jumps outside from the platform, then the reading of spring balance will

a) Increase

b) Become zero

c) Remain same

d) First increases and then becomes zero

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## Set 3

1. Can earth be regarded as a point object when describing its yearly journey around the sun?

a) Yes

b) No

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2. Displacement can be greater than the distance travelled by an object. True or false?

a) True

b) False

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3. Under what condition is the average velocity equal to the instantaneous velocity?

a) Varying velocity

b) Varying speed

c) Constant velocity

d) Constant speed

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4. How is the speed related to magnitude of velocity?

a) Greater

b) Lesser

c) Equal

d) Doesn’t vary

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5. Two balls of different masses (one lighter and one heavier) are thrown vertically upward with same initial speed. Which one will rise to a greater height?

a) The lighter one

b) The heavier one

c) Neither

d) Both the balls

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6. When rain falls vertically downwards, the front screen of a moving car gets wet while the back screen remains dry. True or false?

a) True

b) False

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7. Two trains A and B of length 400m each are moving on twp parallel tracks with a uniform speed of 72km/h in the same direction, with A ahead of B. The driver of B decides to overtake A and accelerates by 1m/s. If after 50s, the guard of B just brushes past the driver of A, what is the original distance between them?

a) 50m

b) 150m

c) 125m

d) 1250m

### View Answer

_{B}-v

_{A}= 0. Hence the train B needs to cover a distance with a= 1m/s, t= 50 s, u = 0 s = ut + 1/2at

^{2}= 1250m

8. A player throws a ball upwards with an initial speed of 29.4m/s. What is the direction of acceleration during the upwards motion of the ball?

a) Upwards

b) Diagonal

c) Projectile motion

d) Vertically downwards

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9. A particle in one dimensional motion with zero speed may have non-zero velocity. True or false?

a) True

b) False

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10. For a particle in one dimensional motion, which of the following is true?

a) Zero speed at any instant may have zero acceleration at the instant

b) Zero speed may have non-zero velocity

c) Constant speed must have zero acceleration

d) Positive value of acceleration must be speeding up

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11. A bullet fired into a fixed target loss half of its velocity after penetrating 3cm. How much further will it penetrate before coming to rest assuming that it faces constant resistance in motion?

a) 1.5cm

b) 1cm

c) 3cm

d) 2cm

### View Answer

^{2}-u

^{2}=2as a= -u

^{2}/8 Now v=0 Initial velocity=u/2 s=1cm Thus the bullet will penetrate a further distance of 1cm before coming to rest.

12. From a building 2 balls A and B are thrown such that A is thrown upward and B is thrown downward. If v_{A} and v_{B} are their respective velocities on reaching the ground, then

a) v_{B} is greater than v_{A}

b) v_{B} = v_{A}

c) v_{B} is lesser than v_{A}

d) Their velocities depend on their masses.

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13. The displacement of the body is given to be proportional to the cube of time elapsed. The magnitude of acceleration of body is

a) Increasing with time

b) Decreasing with time

c) Constant but not zero

d) Zero

### View Answer

^{3}Velocity=ds/dt=3kt

^{2}Acceleration=dv/dt=6kt Clearly acceleration increases uniformly with time.

14. When a ball is thrown vertically upwards, at the maximum height

a) The velocity is zero and therefore there is no acceleration acting in the particle

b) The acceleration is present and therefore the velocity is not zero

c) Acceleration depends on the velocity

d) Acceleration is independent of the velocity

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15. Tom and jerry are running forward with the same speed. They are following a rubber ball at a constant speed v as seen by the thrower. According to Sam, who’s standing on the ground, the speed of the ball is

a) Same as v

b) Greater than v

c) Less than v

d) Zero

### View Answer

_{B}=v+v

_{(Tom or Jerry)}For Sam, the speed of the ball will be greater than v

## Set 4

1. Standing waves are produced in 10m long stretched string. If the string vibrates in 5 segments and wave velocity is 20m/s, its frequency is

a) 2Hz

b) 4Hz

c) 5Hz

d) 10Hz

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2. If vibrations of a string are to be increased by a factor 2, tension in the string must be made

a) Half

b) Twice

c) Four times

d) Eight times

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3. The tension in piano wire is 10N. What should be the tension in the wire to produce a note of double the frequency?

a) 5N

b) 20N

c) 40N

d) 80N

### View Answer

^{‘}=4T=4×10=40N

4. A string in a musical instrument is 50cm long and its fundamental frequency is 800Hz. If a frequency of 1000Hz is to be produced, then required length of string is

a) 62.5cm

b) 50cm

c) 40cm

d) 37.5cm

### View Answer

^{‘}/γ=l/l

^{‘}l

^{‘}=γ/γ

^{‘}×l=800/1000×50=40cm

5. The frequency of a tuning fork is 256. It will not resonate with a fork of frequency

a) 256

b) 512

c) 738

d) 768

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6. An organ pipe closed at one end has fundamental frequency of 1500Hz. The maximum number of overtones generated by this pipe, which a normal person can hear is

a) 12

b) 9

c) 6

d) 4

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7. A tube closed at one end containing air produces fundamental note of frequency 512Hz. If the tube is open at both ends, the fundamental frequency will be

a) 256Hz

b) 768Hz

c) 1024Hz

d) 1280Hz

### View Answer

^{‘}=v/2L=2γ=2×512=1024Hz

8. A closed organ pipe and an open pipe of the same length produce four beats per second, when sounded together. If the length of the closed pipe is increased, then the number of beats will

a) Increase

b) Decrease

c) Remain the same

d) First decrease then remain the same

### View Answer

_{open}-γ

_{closed}=γ/(2L

_{open})-γ/(4L

_{closed}) =Beat frequency Clearly, if the length of the closed pipe is increased, then the beat frequency will increase.

9. At resonance air column of length 20cm resonates with a tuning fork of frequency 450Hz. Ignoring end correction, the velocity of sound in air is

a) 720m/s

b) 820m/s

c) 920m/s

d) 360m/s

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10. Statement: Sound wave cannot propagate through vacuum but light can [Reason:] Sound wave cannot be polarised but light can

a) Both statement and reason are true and reason is the correct explanation of the statement

b) Both statement and reason are true but reason is not the correct explanation of the statement

c) Statement is true but reason is false

d) Both statement and reason are false

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## Set 5

1. A child sits stationary at one end of a long trolley moving uniformly with speed v on a smooth horizontal floor. If the child gets up and runs about on the trolley in any manner, then what is the effect of the speed of the centre of mass of the (trolley+child) system?

a) The speed of the centre of mass increases

b) The speed of the centre of mass decreases

c) The speed of the centre of mass will not change

d) The speed of the centre of mass will first increase and then decrease

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2. A solid sphere rolls down two different inclined planes of the same heights but different angles of inclination. In each case, the ball will reach the bottom

a) With the same speed

b) With different speed

c) With different speed but same time

d) Immediately

### View Answer

^{2}/R

^{2}) ) Velocity of the sphere at the bottom of the inclined plane, v=√(2gh/((1+k

^{2}/R

^{2}))) The sphere will reach the bottom with the same speed v because h is the same in both the cases.

3. A solid sphere rolls down two different inclined planes of the same heights but different angles of inclination. In each case, the ball will

a) Reach the bottom at the same time

b) Will take longer time to roll down one plane

c) Reach the bottom at unpredictable time

d) Reach the bottom at same time and keeps rolling

### View Answer

^{2}/R

^{2}) ) Velocity of the sphere at the bottom of the inclined plane, v=√(2gh/((1+k

^{2}/R

^{2}))) The sphere will take longer time to roll down one plane than the other. It will take larger time in case if the plane with smaller inclination because the acceleration is proportional to sinθ.

4. A hook of radius 2m weighs 100kg. It rolls along a horizontal floor so that its centre if mass has a speed of 20cm/s. How much work has to be done to stop it?

a) 5 J

b) 6 J

c) 2 J

d) 4 J

### View Answer

_{cm}=20cm/s = 0.20ms Work required to stop the hoop = Rotational kinetic energy+Traslational kinetic energy Work required = 1/2 Iω

^{2}+1/2 M(v

_{cm})

^{2}= 4J

5. During rolling, the force of friction acts in the same direction as the direction of motion of the centre of mass of the body. True or false?

a) True

b) False

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6. Where does the centre of mass of two particles of equal mass lie?

a) Inside the body

b) Outside the body

c) Near the first body

d) Midway between them

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7. Two particles A and B, initially at rest, move towards each other under mutual force of attraction. At the instant when the speed of A is v and the speed of B is 2v, the speed of mass of the system is

a) 3v

b) v

c) Zero

d) 1.5v

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8. A smooth sphere A is moving on a frictionless horizontal plane with angular speed ω and the centre of mass velocity u. It collides elastically and head on with an identical sphere B at rest. Neglect friction everywhere. After the collision, their angular speeds are ω_{(A)} and ω_{(B)} respectively. Then,

a) ω_{A} is lesser than ω_{B}

b) ω_{A}=ω_{B}

c) ω_{A}=ω

d) ω_{B}=ω

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9. Moment of inertia of a circular wire of mass M and radius R about its diameter is

a) 1/2 MR^{2}

b) 1/4 MR^{2}

c) 2MR^{2}

d) MR^{2}

### View Answer

_{D}+I

_{D}=1/2 MR

^{2}Therefore, 1/4 MR

^{2}

10. One solid sphere ‘A’ and another hollow sphere ‘B’ are of same mass and same outer radii. Their moments of inertia about their diameters are respectively I_{A} and I_{B}, such that

a) I_{A}=I_{B}

b) I_{A} is greater thab I_{B}

c) I_{A} is lesser than I_{B}

d) I_{A}/I_{B} =ρ_{A}/ρ_{B}