| Date | November 2018 | Marks available | 2 | Reference code | 18N.3.SL.TZ0.3 |
| Level | Standard level | Paper | Paper 3 | Time zone | 0 - no time zone |
| Command term | Explain | Question number | 3 | Adapted from | N/A |
Question
The diagram shows the axes for two inertial reference frames. Frame S represents the ground and frame S′ is a box that moves to the right relative to S with speed v.
When the origins of the two frames coincide all clocks show zero. At that instant a beam of light of speed c is emitted from the left wall of the box towards the right wall. The box has proper length L. Consider the event E = light arrives at the right wall of the box.
Using Galilean relativity,
State what is meant by a reference frame.
explain why the time coordinate of E in frame S is .
hence show that the space coordinate of E in frame S is .
Markscheme
a set of rulers and clocks / set of coordinates to record the position and time of events ✔
ALTERNATIVE 1:
the time in frame S′ is ✔
but time is absolute in Galilean relativity so is the same in S ✔
ALTERNATIVE 2:
In frame S, light rays travel at c + v ✔
so ✔
In Alternative 1, they must refer to S'
x = x' + vt and x' = L ✔
«substitution to get answer»
Examiners report
Syllabus sections
- 17N.3.SL.TZ0.4: Outline the conclusion from Maxwell’s work on electromagnetism that led to one of...
- 19M.3.SL.TZ1.3b: State the speed of the flash of light according to an observer on the ground using Maxwell’s...
- 19M.3.SL.TZ1.3a: State the speed of the flash of light according to an observer on the ground using Galilean...
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18M.3.SL.TZ1.4a.i:
Calculate, according to Galilean relativity, the time taken for a muon to travel to the ground.
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18M.3.SL.TZ2.3a.i:
Calculate, for the reference frame of rocket A, the speed of rocket B according to the Galilean transformation.
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17M.3.SL.TZ2.3b:
A current is established in a long straight wire that is at rest in a laboratory.
A proton is at rest relative to the laboratory and the wire.
Observer X is at rest in the laboratory. Observer Y moves to the right with constant speed relative to the laboratory. Compare and contrast how observer X and observer Y account for any non-gravitational forces on the proton.
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17M.3.SL.TZ2.3a:
State one prediction of Maxwell’s theory of electromagnetism that is consistent with special relativity.
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18N.3.SL.TZ0.4b.i:
Determine the time it takes the probe to reach the front of the rocket according to an observer at rest in the rocket.
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18N.3.SL.TZ0.3b.ii:
hence show that the space coordinate of E in frame S is .
- 18N.3.SL.TZ0.3a: State what is meant by a reference frame.
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18M.3.SL.TZ1.3b.ii:
Deduce whether the overall field around the wire is electric, magnetic or a combination of both according to observer Y.
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17M.3.SL.TZ1.3a:
State what is meant by a reference frame.
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17M.3.SL.TZ1.3b.ii:
State and explain whether the force experienced by P is magnetic, electric or both, in the rest frame of P.
- 16N.3.SL.TZ0.4a: Define frame of reference.
- 19N.3.SL.TZ0.3b(i): State the nature of the force on the particle P in the reference frame of the laboratory.
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19N.3.SL.TZ0.3b(ii):
Deduce, using your answer to part (a), the nature of the force that acts on the particle P in the rest frame of P.
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19N.3.SL.TZ0.3b(iii):
Explain how the force in part (b)(ii) arises.
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17M.3.SL.TZ1.3b.i:
State and explain whether the force experienced by P is magnetic, electric or both, in reference frame S.
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19M.3.SL.TZ1.4a.i:
Estimate in the Earth frame the fraction of the original muons that will reach the Earth’s surface before decaying according to Newtonian mechanics.
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18M.3.SL.TZ1.3a:
State whether the field around the wire according to observer X is electric, magnetic or a combination of both.
- 20N.3.SL.TZ0.3b: State a postulate that is the same for both special relativity and Galilean relativity.
- 20N.3.SL.TZ0.3c(i): Identify the nature of the attractive force recorded by an observer stationary with respect...
- 20N.3.SL.TZ0.4a: The Lorentz transformations assume that the speed of light is constant. Outline what the...
- 20N.3.SL.TZ0.3a: Maxwell’s equations led to the constancy of the speed of light. Identify what Maxwell’s...
- 20N.3.SL.TZ0.3c(ii): A second observer moves at the drift velocity of the electron current in the wires. Discuss...
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16N.3.SL.TZ0.4b:
In the reference frame of the laboratory the force on X is magnetic.
(i) State the nature of the force acting on X in this reference frame where X is at rest.
(ii) Explain how this force arises.
- 19M.3.SL.TZ2.5b: Explain why there is no magnetic force on each proton in its own rest frame.
- 19M.3.SL.TZ2.5c: Explain why there must be a resultant repulsive force on the protons in all reference frames.
- 19M.3.SL.TZ2.4ai: Define an inertial reference frame.
- 19M.3.SL.TZ2.4aii: As the spaceship passes the Earth it emits a flash of light that travels in the same...
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19M.3.SL.TZ2.4b:
Use your answer to (a)(ii) to describe the paradigm shift that Einstein’s theory of special relativity produced.
- 19M.3.SL.TZ2.5a: Outline why there is an attractive magnetic force on each proton in the laboratory frame.
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18M.3.SL.TZ1.4a.ii:
Deduce why only a small fraction of the total number of muons created is expected to be detected at ground level according to Galilean relativity.
