17.3 + 17.5 Energy in a gravitational field

Open Ended

How does the concept of gravitational potential energy change when considering objects far from Earth compared to those near the Earth's surface?

Multiple Choice

Why is it convenient to define the zero of gravitational potential energy at infinity rather than on the Earth's surface?

• Because it simplifies calculations for objects far from Earth

• Because Earth's surface is always the reference point

• Because gravitational acceleration is constant everywhere

• Because potential energy is always zero at Earth's surface

Multiple Choice

Which of the following best describes how to determine the gravitational potential energy (g.p.e.) of a particular mass?

• By measuring the temperature change of the mass

• By calculating the work done on the mass to move it to a point

• By finding the speed of the mass at that point

• By observing the color of the mass

Open Ended

Explain why the gravitational field is always negative.

Multiple Choice

What is the definition of gravitational potential at a point?

• The force per unit mass at a point

• The work done per unit mass in bringing it from infinity to the point

• The energy transferred to a mass at that point

• The speed a mass would have at that point

Multiple Select

Which of the following statements about gravitational potential is/are correct?

• It is zero at infinity.

• It increases as a mass approaches another mass.

• It is more negative near larger masses.

• It is always positive.

Multiple Choice

Which equation gives the gravitational field strength at a distance r from a mass M?

• g = F/m

• g = GM/r^2

• g = -ΔV/Δr

• g = GMm/r^2

Open Ended

Explain how the gravitational potential energy of a rock changes as it falls towards a planet and how this relates to its speed when it hits the surface.

Multiple Choice

Which of the following quantities are needed to calculate the gravitational potential at the surface of the Moon?

• Mass of the Moon and its radius

• Mass of the Earth and its radius

• Distance from Earth to Moon

• Gravitational constant and distance from Sun

Open Ended

A man has a weight of 900 N on the Earth's surface. What would his weight be on the surface of Mercury?

Open Ended

Calculate the gravitational field at the surface of Mercury, given its diameter and mean density.

Open Ended

Explain how the gravitational potential difference equation can be used to determine the energy required to move a satellite from the surface of a planet to a specific orbital height.

Multiple Choice

What is the significance of the equation Δϕ = GM (1/r₁ - 1/r₂) in the context of lifting a satellite from the surface of a planet to an orbital height?

• It calculates the change in gravitational potential energy between two points.

• It determines the speed required for a satellite to escape a planet's gravity.

• It measures the mass of the satellite.

• It finds the time taken for a satellite to complete one orbit.

Open Ended

How does your understanding of gravitational potential energy change when considering objects far from Earth compared to those near the Earth's surface?