Since the net displacement of the cyclist is zero, his average velocity will also be zero.
(c) Average speed of the cyclist:
Average speed
Total path length
Time taken = 10 min
Question 4.10:
On an open ground, a motorist follows a track that turns to his left by an angle of 60° after every 500 m. starting from a given turn; specify the displacement of the motorist at the third, sixth and eighth turn. Compare the magnitude of the displacement with the total path length covered by the motorist in each case.
Answer:
The path followed by the motorist is a regular hexagon with side 500 m, as shown in the
Given figure:
Let the motorist start from point P.
The motorist takes the third turn at S.
Magnitude of displacement
Total path length
The motorist takes the sixth turn at point P, which is the starting point.
Magnitude of displacement
Total path length
The motorist takes the eight turn at point R.
Motorist takes the eight turn at point R
Therefore, the magnitude of displacement is 866.03 m at an angle of 30° with PR.
Total path length = Circumference of the hexagon + PQ + QR
The magnitude of displacement and the total path length corresponding to the required turns is shown in the given table:
Turn | Magnitude of displacement (m) | Total path length (m) |
Third | 1000 | 1500 |
Sixth | 0 | 3000 |
Eighth | 866; 30° | 4000 |