Monday, Febuary 22, 2010

Hello my fellow hard-working classmates. I hope you are all in adventurous mood!

Today in class we corrected "Grade 12 physics: Dynamics" worksheet on static equilibrium problems. I'll show the first and second questions as examples to how they are done.

1. you must solve for Ft first.
sin45= Fn/30N
Fn= 21.2132

Fn=fg
Fg= 2 x (21.2132)
=42N

2. First hint; if you are given the mass, calulate Fg right away by using the equation;
Fg=mg
=(50kg)(9.8N/kg)
=490N
Second calculate the Fn:
sin30= Fn/2Ft
Fn= (sin30)(2Ft)
We know that Fn=Fg (normal force= gravitational force)

490=(sin30)(2Ft)
2Ft=490N/sin30
=980
Here are the answers to the questions 3-5:( please check the blog for more visualization)

3. 346.5N
4. 281 N
5. 56.6N

Remeber to calculate Fg first if you are given mass, them find Fn (regarding the angle) then just substitute.

Also, today we learned about incline planes and how to draw vectors on them. Here is the terminogy:
Fg: gravitaional force is always a straight vertical line from the centre of the object on the incline plane.(arrow point towards the ground or down)

Fperpendicular is the force that is perpendicular to the object on the incline plane(arrow of vector also pointing down relative to the object.)

Fparallel is the one with 2 little lines; refers to a vector that is drawn from the tip(arrow) of Fperpendicular to Fg.

In addition I would like to give you a reminder that tomorrow we will be doing an incline lab, so it is best that you know what the three vectors stand for as mentioned above.

I thought the class today was fun!!! However I would like to thank my friend Ngan who helped me a lot. Maybe it just wasn't the best day for me at school today. It was surprising that My also very good freind Rebecca chose me. She made me feel special. HAHA

Anyways the next scribe will be.... wait let me check the scribe list......how about someone I don't know, for a change let's go with doms...