Comparing G and E Fields

Satellites N and F have the same mass and are in circular orbits about the same planet. The orbital radius of F is greater than that of N. Which is greater for F than for N?

• Gravitational Force on satellite

• Angular speed

• Kinetic energy

• orbital period

Pick the scalar quantity

• Gravitational Potential

• Gravitational Force

• Gravitational Field Strength

• Acceleration

What is the angular speed of a satellite in a geostationary orbit around the Earth?

• 1.2 × 10^–5 rad s^–1

• 7.3 × 10^–5 rad s^–1

• 4.2 × 10^–3 rad s^–1

• 2.6 × 10^–1 rad s^–1

An object moves freely at 90° to the direction of a gravitational field. The acceleration of the object is

• Zero

• 
  opposite to the direction of the gravitational field.

• in the direction of the gravitational field.

• at 90° to the direction of the gravitational field.

1.5 mJ of work is done when a charge of 30 μC is moved between two points, M and N, in an electric field. What is the potential difference between M and N?

• 20 mV

• 20 V

• 45 V

• 
  50 V

Planet N has a gravitational potential –V at its surface. Planet M has double the density and double the radius of planet N. Both planets are spherical and have uniform density. What is the gravitational potential at the surface of planet M?

• 
  –16V

• –8V

• –4V

• 
  –0.2V

A charged spherical conductor has a radius r. An electric field of strength E exists at the surface due to the charge. What is the potential of the spherical conductor?

• 
  r² E

• r E²

• E/r

• r E

The diagram shows equipotential lines for a uniform gravitational field. The lines are separated by 20 m.

An object of mass 4 kg is moved from P to Q. What is the work done against gravity to move the object?

• 7.2 J

• 7.8 J

• 10.2 J

• 
  36 J

Two protons are separated by distance r. The electrostatic force between the two protons is X times the gravitational force between them. What is the best estimate for X?

• 10²⁰

• 10²⁸

• 
  10³⁶

• 
  10⁴²

The radius of a planet is R. The gravitational potential at the surface of the planet due to its mass is −4000 J kg⁻¹. What is the gravitational potential at a distance 2R from the centre of the planet?

• −1000 J kg⁻¹

• −2000 J kg⁻¹

• −4000 J kg⁻¹

• 
  −8000 J kg⁻¹