SAMPLE LESSONS > A LEVEL GRAVITATIONAL FIELD

WEIGHTLESS

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WORKED EXAMPLES

EASY 1

An astronaut in a spaceship orbiting the Earth experiences “weightlessness” because
A

His reaction force is equal and opposite to his weight.
B

He has zero weight.
C

His weight is the only force acting on him.
D

The gravitational field strength at the location of the spaceship is negligible.
Answer

EASY 2

An astronaut is riding in a space capsule in a circular orbit about the Earth at a constant speed as shown in Fig. 11.

The resultant force on the astronaut is
A

zero as the astronaut experience weightlessness.
B

equal to the magnitude of the normal force exerted by the seat on the astronaut.
C

less than its weight and is equal to the between its weight and the normal force exerted by the seat on the astronaut.
D

the gravitational force on the astronaut.
Answer

EASY 3

Assuming the Earth to be a uniform sphere rotating about an axis through the poles, the weight of a body at the Equator compared with its weight at a pole would be
A

greater, because the angular velocity of the Earth is greater at the Equator than at a pole
B

greater, because the weight at the Equator is given by the sum of the gravitational attraction of the Earth and the centripetal force due to the circular motion of the body
C

the same, because the weight is the gravitational attraction of the Earth and for a uniform sphere, even when rotating, this is independent of the body’s position on the Earth
D

smaller, because the gravitational attraction of the Earth must provide both the weight and the centripetal force due to the circular motion of the body
E

smaller, because the gravitational attraction at the pole is greater than that at the Equator
Answer

EASY 4

An object in a space capsule orbiting the Earth seems to be floating.
Which statement describes the forces acting on the object?
A

There are no forces on the object
B

The centrifugal force on the object is equal and opposite to its weight
C

The centripetal force on the object is equal and opposite to its weight
D

The weight of the object is the only force acting on it
Answer

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