Grade 11 · Practice problems
What Physics Is & How We Do It
50 problems, including 18 🔥 challenging (exam-level, multi-step). Work through them on paper, then reveal every answer to check.
1. Identify the independent and dependent variables: a team tests how the range of a launched ball depends on launch angle.
2. Rewrite as a testable hypothesis: 'Heavier objects fall faster.'
3. Is 'the universe is beautiful' a scientific hypothesis? Explain.
4. A student measures how the current in a wire changes with voltage, keeping the wire and temperature the same. Name all three variable types.
5. Why is 'ghosts cause cold spots' hard to treat as science?
6. In science, does calling something a 'theory' make it less certain than a 'law'? Explain.
7. Give the correct order of the scientific method starting from an observation.
8. In an experiment on how drop height affects a ball's bounce height, name the independent and dependent variables.
9. Is 'aliens built the pyramids' a testable scientific hypothesis? Explain.
10. A student changes both the temperature and the pressure of a gas at once and measures its volume. What is the flaw?
11. Give the SI base unit and symbol for length, mass, and time.
12. Rewrite as a testable hypothesis: 'sugar makes children hyperactive.'
13. When testing how light affects plant growth, is 'type of soil' an independent, dependent, or controlled variable?
14. Correct this statement: 'evolution is just a theory, so it's only a guess.'
15. Put the scientific method in order, starting from an observation.
16. Distinguish a hypothesis from a conclusion.
17. Why is measurement so central to physics?
18. Identify the independent and dependent variables: how the current in a bulb depends on the voltage across it.
19. In a drug trial, some patients receive a sugar pill. What is that group called, and why is it used?
20. Name one scientific law and one scientific theory.
21. Why must a scientific result be repeatable by other people?
22. A student concludes 'my plant grew because I talked to it' but also watered and lit it more. What's wrong with the conclusion?
23. In an experiment on how ramp height affects how far a toy car rolls, name the independent and dependent variables.
24. A ruler is worn so that its zero end actually starts 2\ \text{mm} in. Is the resulting error random or systematic?
25. Give the SI base unit and symbol for temperature and for electric current.
26. Is 'a lucky charm improves exam scores' a testable hypothesis, and how would you test it?
27. Among children, shoe size and reading ability are strongly correlated. Does having bigger feet cause better reading? Identify the lurking variable.
28. Why does averaging many repeated readings reduce random error but not systematic error?
29. Define a placebo and explain why a drug trial uses one.
30. State the difference between a blind and a double-blind experiment.
31. Why do scientists treat a distant planet as a 'point mass' when calculating its orbit?
32. A single lab reports a surprising result. Why is that not enough to establish it as accepted science?
33. 🔥 ChallengingClassify each as a law or a theory: (a) F = ma, (b) the theory of evolution, (c) v = f\lambda.
34. 🔥 ChallengingClassify each as a law or a theory: (a) Boyle's law, (b) the atomic theory.
35. 🔥 ChallengingEstimate the number of breaths a person takes in a lifetime (order of magnitude). Assume ~15 breaths per minute and an 80-year life.
36. 🔥 ChallengingIn an experiment, a graph of y against x² is a straight line through the origin with slope 3.0. Write the relationship between y and x.
37. 🔥 ChallengingWhen the quantity x in an experiment is doubled, the measured y increases by a factor of 8. What is the likely relationship between y and x?
38. 🔥 ChallengingEstimate how many times a human heart beats in an average 80-year lifetime (order of magnitude).
39. 🔥 ChallengingEstimate the number of seconds in a year (order of magnitude).
40. 🔥 ChallengingEstimate the total volume of water a person drinks in an 80-year lifetime, assuming about 2\ \text{L} per day.
41. 🔥 ChallengingA car tyre has radius 0.30\ \text{m}. Estimate how many times it rotates over a 100\ \text{km} trip.
42. 🔥 ChallengingEstimate the mass of air in a classroom measuring 10\ \text{m}\times8\ \text{m}\times3\ \text{m}, taking the air density as 1.2\ \text{kg/m}^3.
43. 🔥 ChallengingA graph of distance against time is a straight line through the origin with slope 2.0\ \text{m/s}. Write the relationship and state the speed.
44. 🔥 ChallengingFor a pendulum, a graph of T^2 against length L turns out to be a straight line through the origin. What does this reveal about how the period T depends on L?
45. 🔥 ChallengingIf every length of a cube is tripled, by what factor do its surface area and its volume increase?
46. 🔥 ChallengingEstimate how many heartbeats occur during a 2-hour film, taking a resting rate of about 70 beats per minute.
47. 🔥 ChallengingFour repeated timings give 5.1, 5.2, 5.0, 5.3\ \text{s}. Is the spread more likely random or systematic, and how would you reduce it?
48. 🔥 ChallengingEstimate the number of grains of rice needed to fill a 1\ \text{L} jar, taking one grain as about 0.02\ \text{mL}.
49. 🔥 ChallengingOne hypothesis predicts a new planet at a precise position; a rival idea merely 'fits all past data'. If the planet is found exactly there, which idea gains more support, and why?
50. 🔥 ChallengingNewton's mechanics is still used to design bridges even though relativity is 'more correct'. Explain this using the idea of a domain of validity.