Question 1: Define a dwarf planet and explain how it differs from a regular planet.

Answer: A dwarf planet is a celestial body that orbits the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (almost round) shape, but has not cleared its neighbouring region of other objects. Unlike regular planets, dwarf planets do not dominate their orbital neighbourhood.

Question 2: Describe the main characteristics that distinguish dwarf planets from full-sized planets.

Answer: Dwarf planets are smaller, have not cleared their orbit of other debris, and are less massive than full-sized planets. They are nearly round but share their orbital zone with other objects.

Question 1: Calculate the gravitational potential energy (in joules) of a dwarf planet with a mass of 1.3×10^22 kg and a radius of 1,188 km, relative to a point infinitely far away. Use the formula: U = - (G * M * m) / r, where G = 6.674×10^(-11) N·m²/kg². Assume the mass of the dwarf planet is M, and the test mass m is 1 kg.

Answer: -5.81×10^10 J

Question 2: If the dwarf planet Haumea has an average density of 2.6 g/cm³ and a radius of 785 km, calculate its mass in kilograms. (Note: 1 g/cm³ = 1000 kg/m³)

Answer: Approx. 4.3×10^21 kg

Question 1: Design a simple experiment to estimate the surface temperature of a dwarf planet using remote sensing techniques. Include the key variables involved and safety precautions to consider.

Answer: An experiment could involve analysing the infrared radiation received from the dwarf planet using a spectrometer on a spacecraft. Variables include the wavelength of detected infrared radiation, the distance to the dwarf planet, and the instrument's calibration. Safety precautions involve ensuring the spacecraft's instruments are correctly shielded from external interference and thermal noise, and proper calibration procedures are followed to ensure accurate readings.

Question 1: A dwarf planet has a mean orbital velocity of 0.02 km/s and a radius of 850 km. Using the data, analyse whether this dwarf planet is likely to be in hydrostatic equilibrium. Explain your reasoning.

Answer: The low orbital velocity suggests a small gravitational force, which may indicate the dwarf planet is only just maintaining its shape. Given its size, it is likely in hydrostatic equilibrium if its mass is sufficient to overcome rigid body forces, but further data on its mass would be needed for confirmation.

Question 2: Based on current observations, Pluto's average surface temperature is approximately -229°C. Discuss how this temperature affects the physical state of surface materials and the implications for planetary geology.

Answer: At -229°C, surface materials such as nitrogen and methane ices are in solid form, contributing to a frozen landscape with little to no liquid water. This extreme cold limits geological activity, cold trapping volatile compounds, and results in a geologically inactive surface. These conditions influence the planet's surface features and potential for hosting or preserving certain chemical compounds.

Question 1: Explain the significance of the hydrostatic equilibrium condition in classifying dwarf planets. How does this relate to their physical characteristics and their role in the Solar System? Support your answer with relevant physics principles. (6 marks)

Answer: Hydrostatic equilibrium occurs when a celestial body's gravity is sufficient to shape it into a nearly round form. This condition is crucial for classifying dwarf planets because it indicates significant self-gravity, distinguishing them from irregularly shaped objects. It relates to their physical characteristics, such as spherical shape, and influences their orbital dynamics within the Solar System. Understanding hydrostatic equilibrium involves physics principles like gravity, pressure, and material strength, which are essential for comprehending planetary formation and classification.

Question 1: Discuss how the study of dwarf planets influences the development of space exploration technologies, such as spacecraft design and remote sensing instruments. Include real-world examples where applicable.

Answer: Studying dwarf planets informs spacecraft design by requiring instruments capable of operating in extreme cold and low-gravity environments. Remote sensing technologies developed to analyse their surfaces improve our ability to gather data from distant celestial bodies. For example, NASA's New Horizons mission to Pluto advanced our understanding of such bodies and improved spacecraft technology for future missions.