Physics Help?

2016-09-06 3:26 pm
I just don't get it...

1. A man drops a stone into a water well on
his farm. He hears the sound of the splash
3.86 s later.
How deep is the well? The acceleration due
to gravity is 9.8 m/s
2
and the speed of sound
in air is 324 m/s.
Answer in units of m.

2.
A speedy tortoise can run at 0.1 m/s, and a
hare can run 17 times as fast. In a race, they
start at the same time, but the hare stops to
rest for 2.1 min, so the tortoise wins by a shell
(20 cm).
How long does the race take?
Answer in units of s.

Also, What is the length of the race?
Answer in units of m

回答 (1)

2016-09-06 4:35 pm
✔ 最佳答案
One per post, please.

1) time to fall: t' = √(2h / g)
time for sound to return t" = h / v
and total time t = t' + t"
so
3.86 s = √(2h / 9.8m/s²) + h / 324m/s
which solves to
h = 65.6 m

If you find this helpful, please award Best Answer!


收錄日期: 2021-04-21 21:38:58
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160906072636AAVpNEU

檢視 Wayback Machine 備份