You drop a large rock from a 19 story building. It is 78 meters high.?

[匿名]

2020-11-11 3:37 am

You drop a large rock from a 19 story building. It is 78 meters high. The wind is blowing from the southwest at 3.5 m/s.

A. What is the initial velocity of the rock?

B. How long will it take to hit the pile of leaves that are sitting below?

I am confused, does the wind have an effect on the kinematic equations.

更新1:

I was thinking southwest was in 3 dimensions. But i guess it is in 2 dimensions in the plane. So like the user below said, it wont have an effect on the time it takes to reach the ground. Initial velocity of rock is zero, and solving 0 = -1/2 * 9.8 * t^2 + 78, gives me t = 3.9897828696 or about t= 4.0 seconds

回答 (1)

Morningfox

2020-11-11 3:42 am

I would assume the rock starts off at zero speed. The wind is blowing sideways, not up or down, so it has no effect on the time to fall. (Unless the rock has some sailing effect, like if was flat.)

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