Gravitational Potential

Gravitational potential is the work done moving a 1Kg mass from

• the earths surface to infinity

• From the centre of the earth to infinity

• From infinity to that point in the field

• From that point in the field to infinity

What are the units of gravitaitonal potential

• N/Kg

• J/C

• J/Kg

• J

Which statement best describes gravitational potential at a point?

• The force acting on 1 kg of mass at that point

• The energy required to bring 1 kg from infinity to that point

• The acceleration due to gravity at that point

• The energy required to bring 1 kg from that point to infinity

A point in space has a gravitational potential of –40,000 J/kg. What does this mean?

• A 1 kg mass has –40,000 J of kinetic energy there

• It requires 40,000 J to move 1 kg from infinity to that point

• A 10 kg mass would have 4,000 J potential energy there

• It requires 40,000 J to move 1 kg from that point to infinity

A 2 kg mass is placed at a point with gravitational potential –20,000 J/kg. Its gravitational potential is:

• -10,000 J/Kg

• -20,000 J/Kg

• -40,000 J/Kg

At infinity, gravitational potential is defined as:

• +∞

• 0

• -∞

• Undefined

If the gravitational potential at point A is –50,000 J/kg and at point B is –30,000 J/kg, what does moving from A to B involve for a 1 kg mass?

• Gain of 20,000 J energy

• Loss of 20,000 J energy

• No change in energy

• Gain of 80,000 J energy

Why is gravitational potential always negative near a planet?

• Because V is zero at the centre of the earth and we do work to move away from here

• Because V is zero at infinity and we do work to reach here

• Because V is zero at the surface of the earth and we do work to move away from here

Gravitational potential is inversely proportional to

• Mass of the planet making the field

• Distance from centre of the planet

• Distance from centre of the planet squared

• Mass of the object in the field

Gravitational potential is directly proportional to

• Mass of the planet making the field

• Distance from centre of the planet

• Distance from centre of the planet squared

• Mass of the object in the field