DP Physics (last assessment 2024)

Test builder »

Question 18N.3.SL.TZ0.c.i

Select a Test
Date November 2018 Marks available [Maximum mark: 3] Reference code 18N.3.SL.TZ0.c.i
Level SL Paper 3 Time zone TZ0
Command term Outline Question number c.i Adapted from N/A
c.i.
[Maximum mark: 3]
18N.3.SL.TZ0.c.i

The spacetime diagram shows the axes of an inertial reference frame S and the axes of a second inertial reference frame S′ that moves relative to S with speed 0.745c. When clocks in both frames show zero the origins of the two frames coincide.

A rod at rest in frame S has proper length 1.0 m. At t = 0 the left-hand end of the rod is at x = 0 and the right-hand end is at x = 1.0 m.

Using the spacetime diagram, outline without calculation, why observers in frame S′ measure the length of the
rod to be less than 1.0 m.

[3]

Markscheme

ends of rod must be recorded at the same time in frame S′ ✔

any vertical line from E crossing x’, no label required ✔

right-hand end of rod intersects at R «whose co-ordinate is less than 1.0 m» ✔

 

Syllabus sections