Mechanics question?

2021-01-11 11:47 am
Two stone are thrown form the same point at the same time, vertically upwards with speed 30ms-1, and the other vertically downwards at 30ms-1. Find how far apart the stone are after 3 seconds.
Thanks a lot

回答 (2)

2021-01-11 12:21 pm
✔ 最佳答案
Take g = 9.8 m/s²
h = ut - (1/2) gt²

For the first stone:
h = (30)(3) - (1/2)(9.8)(3)²
Displacement, h = 45.9 m

For the second stone:
h = (-30)(3) - (1/2)(9.8)(3)²
Displacement, h = -134.1 m

Distance apart of the two stones after 3 seconds
= 45.9 - (-134.1)
= 180 m
2021-01-11 4:08 pm
The solution becomes still easy if you assume the first stone moving down wards ( instead of upwards) with an initial velocity of (-)ve 30 m/s and g +ve. Herte you wont need to put the value of g since it gets cancelled out.


收錄日期: 2021-04-24 08:14:09
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