دائروی حرکت اور کششِ ثقل

An object moves at 10 m/s in a circle of radius 5 m. What is its centripetal acceleration?

• 1 2 m/s2
• 2 10 m/s2
• 3 20 m/s2
• 4 50 m/s2

The escape velocity from a planet depends on:

• 1 The mass of the escaping object
• 2 The mass and radius of the planet
• 3 The colour of the planet
• 4 The speed of the planet's orbit only

According to Kepler's third law, the square of the orbital period of a planet is proportional to:

• 1 The radius of the orbit
• 2 The cube of the average orbital radius
• 3 The mass of the planet
• 4 The speed of the planet

The orbital period of a geostationary satellite is:

• 1 90 minutes
• 2 12 hours
• 3 24 hours
• 4 365 days

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

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