Neglecting air resistance, emergency food supplies dropped from an aircraft retain a constant horizontal speed component equal to that aircraft,which is 71m/s. the aircraft altitude is 45m. What's the speed with which the supplies will hit the ground.
And find the horizontal distance of flight of the suplies.
Ans:
Part A
A. 63.3 m/s
B. 66.5 m/s
C. 69.8 m/s
D. 73.3 m/s
E. 77 m/s
F. 80.9 m/s
Part B
A.147m
B. 167m
C. 189m
D. 215m
E. 244m
F. 278m
Find the speed
2008-02-03 12:23 am
回答 (2)
2008-02-03 12:37 am
✔ 最佳答案
Actually, this is a projectile motion. Horizontal and vertical motion are independent. Vertically, by v2 = u2 – 2gs
v2 = 0 – 2(9.8)(-45)
v = 29.7 ms-1
Speed, vp = √(29.72 + 712) = 77 ms-1
Part A: the supplies will hit the ground with a speed 77 ms-1. So, the answer is E.
By s = ut – 1/2 gt2
-45 = 0 – 1/2 (9.8)t2
Time of flight, t =3.03 s
So, the horizontal distance travelled
= horizontal speed X time
= 71 X 3.03
= 215 m
So, the answer is D.
參考: Myself~~~
收錄日期: 2021-04-19 00:41:10
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