DP Physics (last assessment 2024)

Test builder »

Question 17N.3.SL.TZ0.5

Select a Test
Date November 2017 Marks available [Maximum mark: 10] Reference code 17N.3.SL.TZ0.5
Level SL Paper 3 Time zone TZ0
Command term Calculate, Deduce, Define, Determine, Identify Question number 5 Adapted from N/A
5.
[Maximum mark: 10]
17N.3.SL.TZ0.5

Two rockets, A and B, are moving towards each other on the same path. From the frame of reference of the Earth, an observer measures the speed of A to be 0.6c and the speed of B to be 0.4c. According to the observer on Earth, the distance between A and B is 6.0 x 108 m.

(a)

Define frame of reference.

[1]

Markscheme

a co-ordinate system in which measurements «of distance and time» can be made

Ignore any mention to inertial reference frame.

(b)

Calculate, according to the observer on Earth, the time taken for A and B to meet.

[2]

Markscheme

closing speed = c

2 «s»

(c)

Identify the terms in the formula.

u′ =  u − v 1 − u v c 2

 

[1]

Markscheme

u and v are velocities with respect to the same frame of reference/Earth AND u′ the relative velocity

Accept 0.4c and 0.6c for u and v

(d)

Determine, according to an observer in A, the velocity of B.

[2]

Markscheme

− 0.4 − 0.6 1 + 0.24

«–» 0.81c

(e.i)

Determine, according to an observer in A, the time taken for B to meet A.

[2]

Markscheme

γ = 1.25

so the time is t = 1.6 «s»

(e.ii)

Deduce, without further calculation, how the time taken for A to meet B, according to an observer in B, compares with the time taken for the same event according to an observer in A.

[2]

Markscheme

gamma is smaller for B

so time is greater than for A

Syllabus sections