Mathematics: Post your doubts here!

[areeba240]

plzz help me solve this qtn

 

[mohmed ahmed soliman]

The signs in the solution are quite difficult to type, so I did it handwritten, here you goView attachment 60062

thanks
thanks

 

[awesomaholic101]

View attachment 60071
plzz help me solve this qtn

Resolving vertically upward:

3sinx = 6sin20
x = 43.1602

Angle POQ = 43.2+20 = 63.2 deg

Resolving horizontally to the right:
R = 3cosx + 6cos20 = 7.83 N

Are those answers right?

 

[qwertypoiu]

Alright thanks. Can u look at the other questions i posted

Sorry could you just quote them I can't seem to find it.

 

[areeba240]

View attachment 60073
Resolving vertically upward:

3sinx = 6sin20
x = 43.1602

Angle POQ = 43.2+20 = 63.2 deg

Resolving horizontally to the right:
R = 3cosx + 6cos20 = 7.83 N

Are those answers right?

yea the ans is correct but how can u change the figure....the force Q is horizontal and R make angle with Q.

 

[awesomaholic101]

yea the ans is correct but how can u change the figure....the force Q is horizontal and R make angle with Q.

It's the same thing. I've just rotated the diagram. You could otherwise draw a line perpendicular to the resultant as it is, then resolve in the direction of the resultant and in the direction perpendicular to it.
Hope you get what I mean.

 

[areeba240]

It's the same thing. I've just rotated the diagram. You could otherwise draw a line perpendicular to the resultant as it is, then resolve in the direction of the resultant and in the direction perpendicular to it.
Hope you get what I mean.

no what i meant to say was that if the force Q is horizontal then it cannot be 6sin(20) it should be 6

 

[farhan141]

The circled questionsView attachment 60053 View attachment 60054 View attachment 60055

here

 

[awesomaholic101]

no what i meant to say was that if the force Q is horizontal then it cannot be 6sin(20) it should be 6

Yes, if you take Q as horizontal. But I have taken the resultant to be horizontal to make calculations simpler.
Anyway, let's do it that way. You're resolving the forces in the direction of Q and in the direction perpendicular to it.

Resolving horizontally:
Rcos20 = 6 + 3cos(x+20)

Resolving vertically:
Rsin20 = 3sin(x+20)

So basically we are taking the resultant of the forces acting in the horizontal and the vertical directions. Then you will have to use simultaneous eqns to solve. Long process. Try working out both ways anyway and you will get a better understanding.
There may be many ways to solve a problem in mechanics. Your job is to do it the easiest and fastest way.

 

[qwertypoiu]

The circled questionsView attachment 60053 View attachment 60054 View attachment 60055

Question 9b

Spoiler

 

[qwertypoiu]

The circled questionsView attachment 60053 View attachment 60054 View attachment 60055

Question 10:

Spoiler

I realise that my answer isn't exactly what they asked to show, so I don't know how it's supposed to be done. If you find out where I went wrong then please tell me.

 

[qwertypoiu]

The circled questionsView attachment 60053 View attachment 60054 View attachment 60055

The integration question:

Spoiler

 

[qwertypoiu]

The circled questionsView attachment 60053 View attachment 60054 View attachment 60055

Vector question.

Spoiler

 

[qwertypoiu]

The circled questionsView attachment 60053 View attachment 60054 View attachment 60055

7a

Spoiler

 

[farhan141]

Question 10:

Spoiler

View attachment 60097

I realise that my answer isn't exactly what they asked to show, so I don't know how it's supposed to be done. If you find out where I went wrong then please tell me.

Idk too :/

 

[farhan141]

Vector question.

Spoiler

View attachment 60099

Why is the line's direction vector (1,0,0)

 

[farhan141]

And thanks for the rest <3

 

[qwertypoiu]

The circled questionsView attachment 60053 View attachment 60054 View attachment 60055

Spoiler

The last one.

 

[qwertypoiu]

Why is the line's direction vector (1,0,0)

They said parallel to x axis. (1,0,0) is the simplest vector that goes in the direction of x axis. It's a unit vector as well so that's why I chose it. You can choose any vector in the form (s, 0,0), and it will be parallel to x axis.

 

[farhan141]

They said parallel to x axis. (1,0,0) is the simplest vector that goes in the direction of x axis. It's a unit vector as well so that's why I chose it. You can choose any vector in the form (s, 0,0), and it will be parallel to x axis.

so if its parallel to y axis then its 0,s,0?