Multiple choice

A man is driving a car at a speed of 72 kmph towards a hill. He sounds the horn and hears its echo after 2 seconds. At what distance from the hill the horn was sounded. (Velocity of sound = 340 m/s)

  1. 340 m

  2. 360 m

  3. 420 m

  4. 390 m
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Speed of car = 72 kmph = 20 m/s. In 2 seconds, the car travels 40m. Sound travels 340 * 2 = 680m. Total distance covered by sound = 2 * distance_to_hill - distance_car_traveled. 680 = 2d - 40, so 2d = 720, d = 360m.

Keep practicing — related questions