A construction worker's helmet slips and falls when he is 78.4m above the ground. He hears the sound of the helmet hitting the ground 4.23 seconds after it slipped.Find the speed of sound on air.
Answers
Answer:
speed = distance / time
here , the distance is 2 times the height where he is standing because the sound reaches the ground and rebounds.
height = 78.4 m
total distance = 2 × 78.4
= 156.8 m
total time = 4.23 sec
speed = 2d/t
v = 156.8 / 4.23
= 37.06 m/s [ approx. ]
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Answer:
Explanation:
h = 78.4 m
g = 9.81 m/s2
u = Initial speed = 0
Time taken to hear the sound = τ = 4.23 sec
a) Speed of helmet (v = ?)
Use kinematics engine (free fall)
v ^2 = u ^2 + 2gh
= 0 + 2gh
V=√2gh
V=39.22m/s
Time taken by helmet to reach the ground is t = ?
Use kinematics egh.
v = u + gt
t=39.22/9.81
hence t=3.99s
hence time difference is 4.23-3.99=0.24s
speed of sound in air is =78.4/0.24=326.67m/s