ثقل

Newton's law of gravitation says the force between two masses is proportional to:

• 1 The sum of the masses
• 2 The difference of the masses
• 3 The distance between them
• 4 The product of the masses

If the distance between two masses is doubled, the gravitational force becomes:

• 1 Four times
• 2 One quarter
• 3 Half
• 4 Double

The value of g near the surface of the Earth is about:

• 1 0.98 m/s²
• 2 98 m/s²
• 3 9.8 m/s²
• 4 6.67 m/s²

The acceleration due to gravity on the Moon compared with Earth is about:

• 1 Six times greater
• 2 Zero
• 3 One sixth
• 4 The same

A satellite stays in orbit around the Earth because:

• 1 It is very light
• 2 It has no weight
• 3 Gravity provides the centripetal force
• 4 There is no gravity in space

The mass of a body on the Moon compared with its mass on Earth is:

• 1 More
• 2 The same
• 3 Less
• 4 Zero

The gravitational force between two bodies is always:

• 1 Repulsive
• 2 Zero
• 3 Alternating
• 4 Attractive

The value of the gravitational constant G is about:

• 1 3 x 10⁸ N m²/kg²
• 2 6.67 x 10⁻¹¹ N m²/kg²
• 3 9.8 N m²/kg²
• 4 6.67 N m²/kg²

An astronaut in orbit feels weightless because:

• 1 Her mass is zero
• 2 Air pushes her up
• 3 She is in free fall around the Earth
• 4 There is no gravity

The orbital speed of a satellite depends on:

• 1 Its shape
• 2 The mass of the Earth and the orbit radius
• 3 The mass of the satellite only
• 4 Its colour