Kinematics Question 121
Question: An athlete completes one round of a circular track of radius R in 40 sec. What will be his displacement at the end of 2 min. 20 sec? [NCERT 1990; Kerala PMT 2004]
Options:
A) Zero
B) 2R
C) $ 2\pi R $
D) $ 7\pi R $
Show Answer
Answer:
Correct Answer: B
Solution:
Total time of motion is 2 min 20 sec = 140 sec. As time period of circular motion is 40 sec so in 140 sec. athlete will complete 3.5 revolution i.e., He will be at diametrically opposite point i.e., Displacement = 2R.
