Free Weightlessness and Artificial Gravity MCQs with Answers

1. A man of weight \( w \) is standing on an elevator which is ascending with an acceleration \( a \). The apparent weight of the man is

• A. \( mg \)
• B. \( ma - mg \)
• C. \( mg + ma \)
• D. \( mg - ma \)

Explanation: The apparent weight of a person in an elevator is the sum of the gravitational force and the force due to the elevator's acceleration

2. A monkey sits on the pan of a spring scale. The reading of the spring scale will be maximum when the elevator is kept in an elevator

• A. is stationary
• B. accelerate downward
• C. Cable brakes and it falls freely towards the earth
• D. accelerates upward

Explanation: The reading of the spring scale will be maximum when the elevator accelerates downwards. This is because the apparent weight of the monkey is the sum of its actual weight and the force due to the acceleration, and the apparent weight is maximum when the elevator accelerates downward

3. If the weight of a man is 100N and he is sitting in an elevator. Which is moving down with an acceleration of 9.8 m/s², then the apparent weight of the mass will be

• A. 100 N
• B. 1960 N
• C. 200 N
• D. Zero

Explanation: The apparent weight of an object in an elevator is given by the formula W′=W−ma, where ′W′ is the apparent weight, W is the actual weight, m is the mass of the object, and a is the acceleration. In this case, the elevator is moving downward, so a is positive. Plugging in the values, W′=100N−((100/9.8)×9.8m/s2)=0 N.

4. A body of mass m is attached to a spring balance which is attached to the ceiling of an elevator. If the elevator moves up with a certain acceleration, the apparent weight of the body will be

• A. m(g+a)
• B. g(m+ma/g )
• C. a(m+mg/a )
• D. All of these

Explanation: The apparent weight of the body in an elevator depends on the acceleration of the elevator and the gravitational acceleration.Upward acceleration: The apparent weight is m(g + a).Downward acceleration: The apparent weight is m(g - a).

5. Once the space shuttle is in orbit at a radius R from earth's center, what force does the seat exert on the astronaut?

• A. Mg
• B. Zero newton
• C. M/g
• D. Ng/R2

Explanation: In an orbiting space shuttle, the astronaut is in free fall along with the shuttle, experiencing a gravitational force that provides the necessary centripetal force for the circular orbit. The force exerted by the seat on the astronaut is the normal force, and it is what prevents the astronaut from falling through the seat.The gravitational force acting on the astronaut is given by Fgravity =GMm/R2 The centripetal force required for the circular orbit is given by Fcentripetal =mv2 /RIn a stable orbit, Fgravity and Fcentripetal are equal. The normal force exerted by the seat on the astronaut is also equal to Fgravity , as it needs to counteract gravity to keep the astronaut in place.So, Fgravity =Mg, where g is the acceleration due to gravity at the surface of the Earth.

6. In an artificial satellite, an object appears to be weightless when its rotational acceleration 'α' isequal to

• A. g / 4.
• B. g / 2.
• C. g.
• D. 2 g.

Explanation: In an artificial satellite, an object appears weightless when it is in a state of continuous free fall towards Earth. This happens because the satellite and everything inside it, including the object, are accelerating towards the Earth at the same rate as the gravitational pull, g. Therefore, the correct rotational acceleration, α, that results in weightlessness is equal to g. Other values like g/4, g/2, or 2g do not satisfy the condition for weightlessness, as they do not match the gravitational acceleration.