SAT Subject Physics Practice Question 379: Answer and Explanation
75. While a child flies a kite on a breezy day, a burst of wind causes the kite to fly in 1.6 m diameter circles in the sky every second. If the circular motion were converted to a straight down speed, how fast would the kite dive toward the ground?
A. 3.14 m/s
B. 5 m/s
C. 6.28 m/s
D. 9.8 m/s
E. 15.7 m/s
Correct Answer: B
The correct answer is (B). The kite rotates around a 5 m circumference in 1 second (C = 2 πr). Although the path of the kite is circular, it travels 5 m every second. The velocity is v =5m/1s=5m/s.