1. A wagon weighing 1000 kg is moving with a velocity 50 km/h on smooth horizontal rails. A mass of 250
kg is dropped into it. The velocity with which it moves now is ?

A) 12.5 km/hour
B)20 km/hour
C) 40 km/hour
D) 50 km/hour

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Answer is C)

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2. The kinetic energy of two masses m1 and m2 are equal. The ratio of their linear momentum will be ?

A) m1/m2
B) m2/m1
C) sqrt m1/m2
D) sqrt m2/m1

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Answer is C)

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3. Which of the following has the maximum momentum ?

A) A 100 kg vehicle moving at 0.02 ms^{-1}
B) A 4 g weight moving at 10000 cms ^{-1}
C) A 200 g weight moving with kinetic energy 10 ^{-6} J
D) A 20 g weight after falling 1 kilometre

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Answer is D)

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4. A rocket with a lift-off mass 3.5 x 10 ^{4} kg is blasted upwards with an initial acceleration of 10 m/s ^{2} Then the initial thrust of the blast is ?

A) 1.75 x 10 ^{5} N
B) 3.5 x 10 ^{5} N
C) 7.0 x 10 ^{5} N
D) 14.0 x 10 ^{5} N

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Answer is C)

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5. In a rocket of mass 1000 kg fuel is consumed at a rate of 40 kg/s. The velocity of the gases ejected from
the rocket is 5 x 10 ^{4} m/s . The thrust on the rocket is ?

A) 2 x 10 ^{3} N
B) 5 x 10 ^{4} N
C) 2 x 10 ^{6} N
D) 2 x 10 ^{9} N

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Answer is C)

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6. If the force on a rocket moving with a velocity of 300 m/s is 210 N, then the rate of combustion of the fuel
is ?

A) 0.7 kg/s
B) 1.4 kg/s
C) 0.07 kg/s
D) 10.7 kg/s

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Answer is A)

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7. A rocket has a mass of 100 kg. 90% of this is fuel. It ejects fuel vapours at the rate of 1 kg/sec with a
velocity of 500 m/sec relative to the rocket. It is supposed that the rocket is outside the gravitational field.
The initial upthrust on the rocket when it just starts moving upwards is ?

A) Zero
B) 500 N
C) 1000 N
D) 2000 N

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Answer is B)

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8. A man weighs 80kg. He stands on a weighing scale in a lift which is moving upwards with a uniform
acceleration of 5m/s ^{2}. What would be the reading on the scale. (g=10 m/s ^{2}) ?

A) 400 N
B) 800 N
C) 1200 N
D) Zero

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Answer is C)

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9.A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an
acceleration equal to the acceleration due to gravity āgā, the reading on the spring balance will be ?

A) 2 kg
B) (4 x g) kg
C) (2 x g) kg
D) Zero

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Answer is D)

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10. In the above problem, if the lift moves up with a constant velocity of 2 m/sec, the reading on the balance
will Be ?