موضوع مناقشة واجبات فيزياء 101 ترم 111 ‏

You did something wrong with the accelerations you treated the (a) and the (g) as if they were both positive. What you need to know is that gravity is pulling the book downward and acceleration is as been told in the question is UP. So redo the calculation. And for the positive or negative I'm not really sure my self.

 

But according to newton's third law (equal in magnitude opposite on direction) I'd say that if the book is being moved upward its normal force would be reacting downward. But again I'm not really sure just saying what crosses my mind

 

Guy'z in q2: The answer i got it 0.00438


and he wanted it in 2 dicemal , so could it be zero !!?

 

نزلت درجة الهوموورك، من جد عليهم حركات خبيثة يحاولون يمنعوننا من مساعدة بعضنا وياليت لو يرحمونا في المياجر بالمقابل :/

عموماً، طريقة أخوي الفيزيائي (جزاه الله خير) كانت صحيحة وأخذت 3/3

 

1-3




WHAT A DEPARTMENT !!​

 

شباب لو سمحتو اللي عنده السؤال الثالث صح ممكن يحط الأرقام اللي في السؤال، والجواب الصحيح عشان أحله بنفسي، حتى لو انتهى الوقت!

 

حبيبي طلعت لي صح بالموجب 89.1
اخذت 3\3

الله يسامحك خليتني اعيدها 10 مرات

 

Ch05-Lec3

وهذا الواجب الجديد
​

1.111-Q1-Ch05-Lec03

An object of mass 6.3kg rests on a horizontal frictionless surface and an upward vertical force of 4.9N is applied on it. What is the magnitude of the normal force?Take the value of g=9.8 m/s2.
Answer in SI units but do not write units with your answer. Give your answer to 1 decimal place.




2.111-Q2-Ch05-Lec03

A box is sliding down a frictionless ramp inclined at 53.1 degrees to the horizontal as shown in the figure below. What is the acceleration of the box?Take the value of g=9.8 m/s2
Answer in SI units. Give your answer upto 1 decimal place.




http://www.stkfupm.com/webct/RelativeResourceManager?contentID=458472364021

http://www.stkfupm.com/webct/images/shim.gif 3.111-Q3-Ch05-Lec3

A block-1 of mass 16kg and a block-2 of mass 5.0kg are connected by a string as shown in the figure below. If the pulley is massless and the surface is frictionless, then what is the tension in the string?Answer in SI units but do not write units with your answer.



​

http://www.stkfupm.com/webct/RelativeResourceManager?contentID=475679628021

 

اللي عنده استفسار في السؤال الثالث :


3. 111-Q3-Ch05-Lec02

A book is placed on a table in an elevator. Mass of the book is 8.8kg. The elevator starts to move upward and after 5.2s its speed is 7.1m/s. Find the normal force on the book from the table. (Take the value of g = 9.8 m/s2)
Answer in SI units but do not write units with your answer.

Student Response Value
Answer: 98 100%
Score: 1/1




القاعدة اللي اتبعتها هي اللي في الكتاب صفحة 104 تقولك:

Fnet=m(g+a) l==>l Fnet=8.8(9.8+1.37)=98

ملاحظة : a =v/t

​

 

I'm really sorry. But, I'm glad you didn't take my words. However, I'm really confused why is (g) positive like(a) since the book book is accelerating upward and the gravity is pulling it downward. Isn't supposed to be like if (a)=2 then (a+g) should be (2-9.8) I know it is wrong because of my grade on the HW but why? please if someone can explain I'd be more than thankful

 

fn=am
fg+fn=am
fn=-fg+am
fn= - ( - 9.8 *m ) + am

am I right....
I hop it is clear now

 

راح أكتب الحل باختصار للمستعجلين << باقي ما فتحت الماث

و إن شاء الله تكون لي عودة مع الشرح

السؤال الأول :

إستخدم هذا القانون : FN=mg-FApplied




السؤال الثالث :
m1=كتلة الجسم اللي فوق
m2=كتلة الجسم الثاني

إستخدم هذا القانون : T=m1*g*(m2/(m1+m2)) T:Tension force
​

اما السؤال الثاني فحليته غلط بهذا القانون : a=-g*sin

و اعذروني على الاختصار ​

 

السؤال الثاني صح عليك القانون لكن بدون ماينس

اما السؤال الثالث فياليت لو تشرحلنا كيف جبت القانون

مع خالص الشكر

 

.D-law, I will show you a rule that you can apply for this kind of questions

imagine that you're carrying a book with your hands, and suddenly you pull it upward with some acceleration, don't you feel that the book is heavier?
this means that there is a force greater than the usual force (gravity), and this force is pulling it downward
so, f= m(g+a ), and as you see ( g+a) is greater than g, and this explains what I mean.

the same rule you can apply for the opposite case, when you let the book fall down with some acceleration while your hands still in control of the book. don't you feel that the book is lighter?
that means there is a smaller force pulling the book downward, which is equal to ( g-a(

I know it is not easy to understand this example quickly, but I hope this will help you to understand the concept
good luck for you all ^_^

 

قوآنين أخونا مستانس كلهآ صحيحه ..

إلا بالسؤال الثآني بدون الإشارة السالبه "

يعني كذآ الحلول تكون ..
السؤال الأول :
FN=mg-F

السؤال الثاني :
a=g*sin

السؤال الثالث :
m1=كتلة الجسم اللي فوق
m2=كتلة الجسم الثاني

(T=m1*g*(m2/(m1+m2))

وفآلكم الـ3 ^^
وادعولي = )

 

معليش ممكن احد يشرح السؤال الثاني؟ ليش ساين مو كوساين؟

والثالث

 

طيب ياشباب السؤال الاخير بالسق نفقكنت والا لا ؟؟؟


يعني احط الرقم على طول !!

 

قرب ل 2 ديسمل كافي ..

مثال :: 12.3456 حطها 12.35 ..

موفق يا رب

 

جزاكم الله خير، الحين يصير أركز على الماث دون هم الهوموورك.. وهذه أجوبتي بالمرفقات للتجربة

 

كيف استخدمنا القانون للسؤال الثاني

هل افترضوا الماس 1 ؟