IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: yasser37 on October 16, 2010, 02:55:23 pm

Title: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 02:55:23 pm: Hi guys

tomorrow is my monthly exam and I did MANY questions but couldn't do these.

any help would be appreciated

Questions 11 and 12

http://img375.imageshack.us/img375/7665/91760441.png

(http://img375.imageshack.us/img375/7665/91760441.png)

Question 9

http://img269.imageshack.us/img269/3013/37553990.png

(http://img269.imageshack.us/img269/3013/37553990.png)

Question 12

http://img169.imageshack.us/img169/9081/91219203.png

(http://img169.imageshack.us/img169/9081/91219203.png)
Title: Re: Few Mechanics Questions
Post by: Freaked12 on October 16, 2010, 03:24:48 pm: I will 11 and maybe 12
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 03:32:22 pm: that would be great mate

thanks

waiting
Title: Re: Few Mechanics Questions
Post by: nid404 on October 16, 2010, 03:35:09 pm: Gimme some time...
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 04:09:18 pm: tyt m8

I have until tomorrow morning lol
Title: Re: Few Mechanics Questions
Post by: iluvme on October 16, 2010, 04:27:15 pm: Quote from: yasser37 on October 16, 2010, 02:55:23 pm
Hi guys

tomorrow is my monthly exam and I did MANY questions but couldn't do these.

any help would be appreciated

Question 12

http://img169.imageshack.us/img169/9081/91219203.png

(http://img169.imageshack.us/img169/9081/91219203.png)

12. (a) Is it 40.52m?
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 04:32:18 pm: 62.8m
Title: Re: Few Mechanics Questions
Post by: iluvme on October 16, 2010, 04:35:14 pm: Quote from: yasser37 on October 16, 2010, 04:32:18 pm
62.8m

I'm blank. Sorry.
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 04:39:27 pm: Thanks for trying

I appreciate it
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 05:12:49 pm: Is it 36.9 for 11)(angle of projection) ??? ???
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 05:26:10 pm: it's 35.9

u r SO CLOSE!

aaah

thanks anyway
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 05:32:24 pm: Quote from: yasser37 on October 16, 2010, 05:26:10 pm
it's 35.9

u r SO CLOSE!

aaah

thanks anyway

i used 9.8 as the value of g.i think that was my mistake :-\
Title: Re: Few Mechanics Questions
Post by: nid404 on October 16, 2010, 05:34:05 pm: I did the 9th one....airplane thingy *attached*
Title: Re: Few Mechanics Questions
Post by: nid404 on October 16, 2010, 05:44:24 pm: Are the others all left to be done? I'll try..
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 05:51:56 pm: Quote from: yasser37 on October 16, 2010, 02:55:23 pm
Hi guys

tomorrow is my monthly exam and I did MANY questions but couldn't do these.

any help would be appreciated

Questions 11 and 12

http://img375.imageshack.us/img375/7665/91760441.png

(http://img375.imageshack.us/img375/7665/91760441.png)

i found my mistake here :).........don't worry about the g .......g cancel out from equation ;)
12) is same as 11)......the only difference is u have to find initial speed instead of angle :)........if u don't understand than i can explain u :)
Title: Re: Few Mechanics Questions
Post by: nid404 on October 16, 2010, 05:53:58 pm: Is this both 11 and 12?
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 06:00:30 pm: 11 and 12 are almost same :).....i modified my previous post :)
Title: Re: Few Mechanics Questions
Post by: nid404 on October 16, 2010, 06:02:30 pm: oh ok :)

So which one is left to be done? :-\
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 06:08:06 pm: the last one ...i am doing it ::)
Title: Re: Few Mechanics Questions
Post by: nid404 on October 16, 2010, 06:10:23 pm: Wohkay :)
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 06:15:47 pm: Quote from: asiftasfiq93 on October 16, 2010, 05:51:56 pm
i found my mistake here :).........don't worry about the g .......g cancel out from equation ;)
12) is same as 11)......the only difference is u have to find initial speed instead of angle :)........if u don't understand than i can explain u :)

I LOVE YOU lol

just one doubt

why did we use -0.5 and 3.5

why not use 0.5 as positive and keep 3.5 as 4

will we get the same answer?
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 06:16:33 pm: Garfield

Thank you for solving that

all clear now m8

thanks
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 06:21:29 pm: Quote from: yasser37 on October 16, 2010, 06:15:47 pm
I LOVE YOU lol

just one doubt

why did we use -0.5 and 3.5

why not use 0.5 as positive and keep 3.5 as 4

will we get the same answer?
i am showing you...need some time :)
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 06:22:13 pm: tyt m8

I am really thankful
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 06:54:21 pm: What is the answer for 12) b is it 10.98?
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 07:13:23 pm: it's 11 so yeah

can't wait for it lol
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 07:23:07 pm: the last part is tough :'( :'( :'(...need to think for a while :'(
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 16, 2010, 07:29:48 pm: ok m8
tyt

am gonna sleep now

just please dont forget the -0.5 and 3.5 please

am gonna check tomorrow b4 i head to skool
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 07:32:13 pm: ok no problem :)

good nite :)
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 10:53:42 pm: Sorry unable to find the value of T :(
Here 12 a&b
Title: Re: Few Mechanics Questions
Post by: S.M.A.T on October 16, 2010, 11:35:59 pm: Quote from: yasser37 on October 16, 2010, 06:15:47 pm
I LOVE YOU lol

just one doubt

why did we use -0.5 and 3.5

why not use 0.5 as positive and keep 3.5 as 4

will we get the same answer?
When we use motion formula like s=ut+0.5at^2,v^2=u^2+2as etc ,the 's' represent resultant displacement, for example a ball is is thrown at an angle from a cliff which 5m from ground level so resultant vertical displacement is -5m

The negative sign indicates that the ball moved extra 0.5m downward i.e resultant vertical displacement is 0.5m downward shown in diagram 1
U can not keep 3.5 as 4 because when the ball moved horizontally 10m, the ball has a resultant vertical displacement of 3.5 shown in diagram 2

If u still have problem then ask me :)
Title: Re: Few Mechanics Questions
Post by: yasser37 on October 17, 2010, 03:04:16 am: Thanks a lot m8

really helped me there

+rep
Title: Re: Few Mechanics Questions
Post by: cooldude on October 17, 2010, 06:29:23 am: for the third part solve the equation
tan 20=[30+(12t-5(t^2))]/16t
lets consider A as the origin, angle RAB basically means the angle that R's horizontal and vertical displacements make wrt A. so R's horizontal displacement is 16t and its vertical displacement wrt A is 30+12t-5(t^2), see the diagram attached to get a clearer idea of the explanation, p.s. sorry about the bad handwriting

in the diagram RAB is A, and y and x are the vertical and horizontal displacements respectively.