1.The pilot of an aircraft has to get to a point 300 km due north in 1 h.
Ground control reports that there is a crosswind of 50 km/h toward 370 N of E.
(a) What is speed of the plane?
(b) What is the required heading of the plane?
2.A bag of cement whose weight is W=200.0 N hangs in equilibrium from three wires as figure. 圖:http://imgur.com/txTTk0n
Two of the wires make angle 角1 = 60度 and 角2 = 45度 with the horizontal.
Find the tensions T1 and T2?
http://imgur.com/txTTk0n
3.A sled of mass 5kg is on a us=0.1 and uk=0.1 friction slope inclined at 37度 to the horizontal. It is pulled by a rope whose tension is 40N and which makes an angle of 30度 with the slope, as figure. 圖:http://imgur.com/txTTk0n
Find the acceleration of the sled and the normal force due to the incline?
http://imgur.com/txTTk0n
這是我之前考試完的題目 但老師沒有講解 而這是其中幾題我不太熟悉的題目
而且我也沒有正解 希望回答的大大能夠在解答後面用中文解釋為何如此列式
讓我更能夠了解怎麼解類似題目 拜託了20點奉上
大一物理題求詳解 急!
2014-10-25 5:48 am
回答 (2)
2014-11-02 7:01 pm
✔ 最佳答案
1(a)300j-50(cos37i+sin37j)=270j-40i
=-40i+270j
speed of the plane =40^2+270^2開根號=272.9
(b)atan(270/-40)=atan(-6.75)=98.43°
2.ΣFy=Tsin30+N-mgcos37=0
=Tsin30+n-mgcos37=0
=20+n-5*9.8*0.8=0
n=19.2
ΣFx=Tcos30-n*us-mgsin37=ma
=40*√3/2-19.2*0.1-5*9.8*0.6
=20√3-1.90-29.4=5a
a=20√3-1.90-29.4/5
a=0.642(m/s^2)
參考: 之前問過和你類似的題目 由麻辣知識長解答 現在我會了
2014-11-02 6:04 pm
看來是想混大學四年的廢物。不好意思，已加入黑名單
收錄日期: 2021-04-27 21:27:37
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20141024000010KK06756