[練習]普物第二章例題

[vbcaeo ()]

普物第二章老師有勾選8題例題，考試也是類似這種題目。
因為很多人沒有買課本，應同學之要求把題目和答案打上來。
(答案照課本寫，與實際計算結果可能有些誤差)

題目01
A person is standing on a bathroom scale. Which of the following is
not a force exerted on the scale：a contact force due to the floor, a
contact force due to the person’s feet, the weight of the person, the
weight of the scale？
翻譯：
一個人站在浴室磁磚上，哪個不是磁磚的外力：
地板造成的接觸力、腳造成的接觸力、人的重量、磁磚的重量
Ans：
the weight of the person(人的重量)
Sol：
人的重量是地球和人之間的萬有引力造成的超距力，並無作用在地板瓷磚上。



題目17
A sailboat, tied to a mooring with a line, weights 820N.The mooring line
pulls horizontally toward the west on the sailboat with a force of 110N.
The sails are stowed away and the wind blows from the west. The boat is
moored on a still lake - no water currents push on it. Draw a free-body
diagram for the sailboat and indicate the magnitude of each forece.
翻譯：
一艘停泊在岸邊的小船重820NT，繫船索用一個水平向西110牛頓的力量拉著船，
而帆則因西邊吹來的風而有一推力，船是停泊在一個平靜的湖面－沒有水波施力
於船。畫出作用於船上的力圖並預測各個力量的大小。
Ans：
                           ↑820N向上：湖水給船的正向力
   110N向西：繫船索的張力←船→110向東：風施給帆（船）的力
                           ↓820N向下：船和地球的萬有引力
Sol：
如解答


題目29
A barge is hauled along a straight-line section of canal by two horses
harnessed to tow ropes and walking along the tow paths on either side of
the canal. Each horse pulls with a force of 560N at an angle of 15°with
the centerline of the canal.Find the net force on the barge.
翻譯：
一艘運河上的平底船被兩匹沿著運河旁小徑行進的馬以直繩拖行著，兩匹
馬各以560牛頓、與運河中心線夾角15度的力量拖行著船，試找出船的合力。
Ans：
1k N foward
Sol：
560N*2*cos15°=1081.83693

題目41
.A young south African girl has a mass of 40.0 kg.
(a)What is her weight in newtons ?
(b)If she came to the United States, what would her weight be in pounds
   as measured on an American scale? Assume g=9.80N/kg in both locations.
翻譯：
有個南非的女孩質量為40公斤。
(a)女孩的重量是多少牛頓?
(b)若她到了美國，換算成美國單位，那是多少磅重？假設兩地的g=9.80N/kg
Ans：
(a)392(b)88.1
Sol：
(a)40*9.8=392
(b)一公斤約等於2.20462磅，40*2.20462=88.18480


題目57
A horse is trotting along pulling a sleigh through the snow. To move the
sleigh,of mass m, straight ahead at a constant speed, the horse must pull
with a force of magnitude T.
(a)What is the net force acting on the sleigh?
(b)What is the coefficient of kinetic friction between
   the sleigh and the snow?
翻譯：
一匹馬拉著雪撬，為了使雪橇(質量為m)以等速移動，馬必須施加張力T。
(a)雪橇所受合力？
(b)雪橇與雪之間動摩擦造成的摩擦係數為何？
Ans：
(a)0(b)T/mg
Sol：
(a)等速，所以合力為0
(b)動摩擦力=馬的拉力，T=mg*摩擦係數，移項可得


題目69
A pulley is attached to the ceiling. Spring scale A is attached to the
wall and a rope runs horizontally from it and over the pulley. The same
rope is then attached to spring scale B. On the other side of scale B
hangs a 120-N weight . What are the readings of the two scales A and B?
The weights of the scales are negligible.
翻譯：
一個滑輪固定在天花板上。一個彈簧秤A一端連接牆壁一端連接繩子，繩子水平穿
過定滑輪後垂下，與彈簧秤B連接，而彈簧秤B另一端與一個120Nt的重物連接。兩
彈簧秤的讀數各為何?彈簧秤的重量可忽略。
Ans：
都是120N
Sol：
直繩上各點張力皆相等    附圖:牆－彈簧A－滑輪
                                        ∣
                                      彈簧B
                                        ∣
                                    120N的重物
題目85
An airplane is cruising along in a horizontal level flight at a constant
velocity, heading due west.
(a)If the weight of the plane is 2.6×10000 N,what is the net force on
   the plane?
(b)With what force does the air push upward on the plane?
翻譯：
一架飛機以固定的速度朝向著正西方水平飛行。
(a)如果飛機重2.6×10000 N，那飛機的淨力是多少？
(b)多少朝上的力施加在飛機機身上？
Ans：
(a)0
(b)2.6×10000 N
Sol：
(a)等速移動，合力為0(b)水平移動，空氣給予飛機的浮力=飛機的重量

題目97
A computer weighing 87 N rests on the horizontal surface of your desk.
The coefficient of friction between the computer and the desk is 0.60.
(a) Draw a  free-body diagram for the computer.
(b) What is the magnitude of the fricitional force acting on the computer?
(c) How hard would you have to push on it to get it to start to slide across
 the desk?
翻譯：
有一台重87牛頓的電腦水平的放在你的桌面上，電腦與桌面的共同摩擦係數為0.6。
(a)為你的電腦畫一張自由體圖(FBD)
(b)作用於電腦上的摩擦力有多大
(c)你需要施多大的力才能使電腦移動
Ans：
    ↑桌子給電腦的正向力
(a)電腦
    ↓電腦和地球的萬有引力
(b)0
(c)52 N
Sol：
(a)如圖
(b)水平方向無外力，所以淨摩擦力等於0
(c)87 N *0.6=52.2 N

用完之後的感想一整個就是so sad，ptt不好編輯的說......
影印店也不可能幫忙影印書本題目。一題一題輸入word裡面也很累的說，
所以......誰家裡有高解析度的掃描機可以直接將題目掃描成文字檔的，
這樣可以省掉很多功夫和時間
ps.需要例題的word檔的人在跟我要

--
※ 發信站: 批踢踢實業坊(ptt.cc) 
◆ From: 59.126.51.177
推 ooxx1129:好辛苦阿= =...替鵬宇跟你說一聲"辛苦了"!!
推 gmoigi:彥霆辛苦阿!!抬頭看看時間...快五點了...我可以幫打!
推 etanimodhaon:哀實在是太累了.....看起來就很累.....
推 yuki0404:狂推!我快要哭了....
推 cinnachang:狂推狂推!!!!!整個讓我有想飆淚的衝動~感動到不行!!!!
推 yuki0404:我再推~彥霆真的很辛苦~要讓全世界知道!
推 cinnachang:今天睡眠不足就是因為這個喔?明明還在生病說...別太逞넠
→ cinnachang:強了
推 assdert:辛苦你了,真希望你來當微積分組員啊~~~@@
推 inuchining:彥霆別太勉強自己摟  你真的太努力了~感動!!!!!
推 yuki0404:彥霆要好好保重身體~
推 etanimodhaon:夜貓子就是夜貓子= =+
→ vbcaeo:大家都被PO文的時間給誤會了...我沒用這個用了一整晚啦!
推 gmoigi:我有意誤導大家XD  哈哈  但你還是很辛苦!!
推 ff7ff8d2:彥霆真是辛苦你了^^,謝謝你做的這麼好~