Our Place in the Universe | OCR A-Level Physics B (Advancing Physics) (H557)
Our Place in the Universe
- 76 questions
- 5 subtopics
- The physics content, examined on all three papers
- Component 01, Component 02 and Component 03
Our Place in the Universe is examined in all three written papers — the specification states that Components 01, 02 and 03 each assess content from across all the teaching modules, so nothing is confined to one paper.
It covers radar measurement of distance and velocity, distance measured in units of time, relativistic time dilation, evidence for the hot big bang and logarithmic scales of magnitude.
Sample questions from Our Place in the Universe
Answer each one closed book first, then open the answer.
-
Radar measurement of distance and velocity
Why is radar unsuitable for measuring distances to other stars?
Show the answer
The reflected pulse would be far too weak to detect after spreading over such distances, and the round trip would take years. -
Radar measurement of distance and velocity
Why must a radar pulse be short if small changes in distance are to be resolved?
Show the answer
The uncertainty in the arrival time is roughly the pulse duration, so a shorter pulse gives a smaller uncertainty in the distance. -
Distance measured in units of time
How far away is an object described as one light-second distant?
Show the answer
It is 3.00 × 10⁸ m away. -
Distance measured in units of time
How far does light travel in one nanosecond?
Show the answer
It travels about 0.30 m. -
Relativistic time dilation
What is the value of γ for an object at rest, and what does it mean?
Show the answer
It is 1, which means there is no time dilation at all. -
Relativistic time dilation
What happens to γ as the speed approaches the speed of light?
Show the answer
It rises without limit, tending to infinity as v approaches c. -
Evidence for the hot big bang
Why does the recession of almost all galaxies not put the Earth at the centre of the universe?
Show the answer
Space is expanding everywhere, so an observer in any galaxy would see all the others moving away in just the same way. -
Evidence for the hot big bang
What temperature is associated with the cosmic microwave background?
Show the answer
It corresponds to a temperature of about 2.7 K.
The 5 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Radar measurement of distance and velocity | Recall questions on timing an echo and why the time is halved, distances to the Moon and planets, relative velocity from successive pulses, pulse length and timing uncertainty, and the method's limits. | 15 |
| Distance measured in units of time | Recall questions on the invariance behind it, light-years and light-seconds in metres, the modern definition of the metre, seeing objects as they were, and the limit on what can be observed. | 15 |
| Relativistic time dilation | Recall questions on γ = 1/√(1 − v²/c²) and its values at rest, 0.60c and 0.80c, time dilation and dilated intervals, why it goes unnoticed, muon lifetimes as evidence, γ growing without limit near c, the speed at which γ is 2.0, why massive objects cannot reach c, satellite navigation, and the symmetry between observers. | 15 |
| Evidence for the hot big bang | Recall questions on cosmological red-shift, Hubble's law and the Hubble constant with its units, z = Δλ/λ = v/c, recession speed and distance calculations, why the Earth is not at the centre, estimating the age of the universe from 1/H₀ and its limits, the cosmic microwave background and its 2.7 K temperature, and the abundance of helium. | 16 |
| Logarithmic scales of magnitude | Recall questions on logarithmic scales and why astronomy uses them, orders of magnitude, the sizes of atoms, nuclei and the Earth, the distances to the nearest star and the edge of the observable universe, the masses of the Sun and a proton, placing values on a logarithmic scale, brightness decades, reading ratios, and why the scale has no zero. | 15 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
-
Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
-
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
-
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR A-Level Physics B (Advancing Physics) Active Recall Guide
Every topic, not just this one. 2,455 questions with their answers.