Space and Environment

Physics, HSSC-Punjab Second Year. This chapter is split into 46 topics and has 1,125 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Luminosity of a star and the Stefan-Boltzmann law 22 questions
2. Big Bang timeline and cosmic ideas 20 questions
3. Introduction to space and environment 22 questions
4. Salinity, mass of salt and floating in sea water 24 questions
5. Rotation of the Earth, angular momentum and energy budget 24 questions
6. Comparing two stars with Wien's displacement law 28 questions
7. Radiant flux intensity and standard candles 22 questions
8. Redshift, Hubble's law and the age of the universe 28 questions
9. Speeds on the rotating Earth at different latitudes 26 questions
10. Hubble's constant: unit conversions and age estimates 26 questions
11. Climate system: which component does it belong to? 30 questions
12. Energy budget, albedo and greenhouse effect: reasoning 25 questions
13. Cosmic distances: light-years, parsecs and light travel time 26 questions
14. Surface temperature, luminosity and radius of a star 24 questions
15. Further redshift and recession-speed problems 24 questions
16. Spectra of stars, redshift, Hubble's law and the Big Bang 28 questions
17. Luminosity calculations using the Stefan-Boltzmann law 28 questions
18. Wind belts, pressure zones and atmospheric cells 27 questions
19. Choosing the right law or formula for a space problem 24 questions
20. Comprehensive and constructed-response questions of the chapter 23 questions
21. Wien and Stefan-Boltzmann laws: reasoning and comparison 26 questions
22. Ocean currents and thermohaline circulation 21 questions
23. Specific angular momentum of moving air 24 questions
24. Earth's climate system and energy budget 22 questions
25. Luminosity versus radiant flux: comparing the two ideas 25 questions
26. Absorption, emission and continuous spectra: reasoning 22 questions
27. Satellite remote sensing 20 questions
28. Solar flux, the Sun's luminosity and energy received by the Earth 28 questions
29. Wien's displacement law calculations 28 questions
30. Radiant flux intensity calculations 28 questions
31. Redshift of identified spectral lines 28 questions
32. Climate system components: definitions and interactions 24 questions
33. Stars compared with the Sun in solar units 26 questions
34. Atmospheric circulation and the Coriolis effect 20 questions
35. Ocean circulation: speeds, times and heat carried 24 questions
36. Blackbody radiation and Wien's displacement law 23 questions
37. Satellite remote sensing: identify the step 24 questions
38. Satellite remote sensing: applications and reasoning 24 questions
39. Salinity, density and ocean circulation: reasoning 26 questions
40. Estimating the radius of a star 20 questions
41. Redshift and blueshift: interpreting observations 24 questions
42. Photon energy and the peak wavelength of a hot body 26 questions
43. Blackbody facts and everyday examples 24 questions
44. Exercise questions and conceptual reasoning on space and environment 20 questions
45. Standard candle distance problems 24 questions
46. Expanding universe and the balloon model 23 questions

Sample questions: Space and Environment

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. A blackbody is an object that:

• A. emits radiation only at a single wavelength
• B. reflects all of the radiation falling on it
• C. is always black in colour and at a low temperature
• D. absorbs all the radiation falling on it and emits radiation at all wavelengths perfectly(correct answer)

Answer: D.This is the chapter's definition, so the answer is absorbs all the radiation falling on it and emits radiation at all wavelengths perfectly.

Q2. Satellite remote sensing can be used to track:

• A. only the speed of the cars on the main roads
• B. only the phases of the Moon during a month
• C. only the position of the stars in the night sky
• D. deforestation, climate change, ocean temperatures and atmospheric composition(correct answer)

Answer: D.The chapter lists these applications, so the answer is deforestation, climate change, ocean temperatures and atmospheric composition.

Q3. The Earth's energy budget refers to the balance between:

• A. solar energy absorbed by the Earth and the energy it radiates back into space(correct answer)
• B. the energy of the Moon and the energy of the Earth
• C. the energy of the winds and the energy of the ocean tides
• D. the heat of the core and the heat of the mantle

Answer: A.This is the definition in the chapter, so the answer is solar energy absorbed by the Earth and the energy it radiates back into space.

Q4. How would the spectrum of light from galaxies look different if the universe were not expanding?

• A. the lines would be at their laboratory wavelengths with no systematic redshift(correct answer)
• B. all lines would vanish from the spectrum of every galaxy
• C. all lines would be redshifted by an even larger amount
• D. all lines would be blueshifted by the same amount

Answer: A.No expansion means no cosmological shift, so the answer is the lines would be at their laboratory wavelengths with no systematic redshift.

Q5. If the Earth suddenly stopped rotating, how would it affect winds and ocean currents?

• A. the oceans would freeze over completely
• B. the Coriolis deflection would vanish, changing the patterns of winds and currents(correct answer)
• C. all winds would stop for ever over the whole Earth
• D. nothing would change in the winds or the currents

Answer: B.The rotation shapes circulation, so the answer is the Coriolis deflection would vanish, changing the patterns of winds and currents.

Q6. The reason standard candles are so useful is that for them:

• A. the distance is known, so the temperature can be found from the flux
• B. the luminosity is known, so the distance can be found from the measured flux(correct answer)
• C. the temperature is known, so the age can be found from the flux
• D. the flux is known, so the luminosity can be found from the distance

Answer: B.The unknown is then only the distance, so the answer is the luminosity is known, so the distance can be found from the measured flux.

Q7. Which statement about remote sensing is correct?

• A. it uses only ground-based thermometers
• B. it works only at night
• C. it monitors the Earth's environment from space using sensors aboard spacecraft(correct answer)
• D. it requires touching the target

Answer: C.This is the definition in the chapter, so the answer is it monitors the Earth's environment from space using sensors aboard spacecraft.

Q8. How does the concept of luminosity help astronomers understand the nature of stars? It tells them the:

• A. age of the star only
• B. number of planets around the star
• C. colour of the star's light only
• D. total power the star emits, which relates to its size and surface temperature(correct answer)

Answer: D.L depends on radius and temperature, so the answer is total power the star emits, which relates to its size and surface temperature.

Q9. How does Hubble's law lead to the Big Bang theory?

• A. reversing the expansion places all matter in a hot dense state about 13.8 billion years ago(correct answer)
• B. reversing the expansion shows the Sun is the centre
• C. reversing the expansion places all matter at the Earth
• D. reversing the expansion shows the universe is static

Answer: A.The beginning is the Big Bang, so the answer is reversing the expansion places all matter in a hot dense state about 13.8 billion years ago.

Q10. How do ocean salinity and thermohaline circulation help transport heat from the equator toward the poles?

• A. cold surface water moves poleward and then rises as warm fresh water
• B. warm surface water moves toward the equator and sinks there
• C. warm surface water moves poleward and then sinks as cold salty water and returns at depth(correct answer)
• D. salt water cannot move at all

Answer: C.The loop moves heat poleward, so the answer is warm surface water moves poleward and then sinks as cold salty water and returns at depth.