in a certain instance, a plane flying horizontally was at a distance 5000 m vertically above Timmy's head. After 10 seconds, it was 6000 m from Timmy's head. What was the speed of the plane in km/h?
(Correct your answer to 2 significant figures)
Pythagoras'
2007-12-12 6:04 am
回答 (2)
2007-12-12 6:38 am
✔ 最佳答案
Let the distance travelled by the plane in this 10 seconds be x m.By Pythagoras' Theorem,
x^2 + (5000)^2 = (6000)^2
x^2 = 11000000
x = 3316.625...
The speed of the plane
= 3316.625m / 10s
= 3.31625 km / 10s
= 0.331625 x 3600 km/h
= 1193.98... km/h
= 1200 km/h (2 sig. fig.)
Therefore, the speed of the plane is 1200 km/h.
If there is any mistake, please inform me.
參考: My Maths knowledge
2007-12-12 6:37 am
By Pythagoras' Theorem,
Distance that the plane flied in 10 seconds
=√((6 000m)^2-(5 000m)^2)
=1 000√11 m
=√11 km
Time that the plane used
=10s
=(10/3 600)h
=(1/360)h
Therefore, the speed=√11 km / (1/360)h=1 200km/h(cor. to 2 sig. fig.)
Distance that the plane flied in 10 seconds
=√((6 000m)^2-(5 000m)^2)
=1 000√11 m
=√11 km
Time that the plane used
=10s
=(10/3 600)h
=(1/360)h
Therefore, the speed=√11 km / (1/360)h=1 200km/h(cor. to 2 sig. fig.)
收錄日期: 2021-04-13 14:41:50
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20071211000051KK04030