The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

Help M1 vectors question

part 3 I have absolutely no clue what to do
m1 jun 05 Q5.png79.2KB
Reply 1
Avatar for Notnek
Notnek
21
Original post by Chemgawd99
part 3 I have absolutely no clue what to do

You can use part ii to help.

You have shown that the path of the particle follows a parabola. There will be a point on this parabola where the particle is moving at 45 degrees to the axes. Think about gradient.

Please post your working / thoughts if you gets stuck.
Reply 2
Avatar for KaylaB
KaylaB
20
Original post by Chemgawd99
part 3 I have absolutely no clue what to do


If you think about what the angle of 45 degrees actually looks like

Spoiler


think about what very simple Cartesian equation it is the same as.
Once you have the equation of that you now have 2 equations of 2 lines and thus need to find the point where they intersect, so you can make them equal to each other and solve for x, and remember to substitute back in the x value to find the y value :h:
Reply 3
Avatar for Notnek
Notnek
21
Original post by KaylaB
If you think about what the angle of 45 degrees actually looks like

Spoiler


think about what very simple Cartesian equation it is the same as.
Once you have the equation of that you now have 2 equations of 2 lines and thus need to find the point where they intersect, so you can make them equal to each other and solve for x, and remember to substitute back in the x value to find the y value :h:

I don't think this is right since you're looking for where the direction is at an angle of 45. Your method will give you where the x coordinate is equal to the y-coordinate but that isn't necessarily where the direction is at a 45 degree angle.
Reply 4
Avatar for Chemgawd99
Chemgawd99
OP
9
Original post by KaylaB
If you think about what the angle of 45 degrees actually looks like

Spoiler


think about what very simple Cartesian equation it is the same as.
Once you have the equation of that you now have 2 equations of 2 lines and thus need to find the point where they intersect, so you can make them equal to each other and solve for x, and remember to substitute back in the x value to find the y value :h:

thanks but im still a bit lost. I can only think of y=x
Reply 5
Avatar for Chemgawd99
Chemgawd99
OP
9
the mark scheme says dy/dx = 1. that's from the line y=x I guess. setting the differenial of Cartesian equation to 1 and solving gave me the right x coordinate 1/8 I then subbed into y and got -15/16 which is right. HOWEVER, I don't understand why this is :s-smilie:
Reply 6
Avatar for KaylaB
KaylaB
20
Original post by notnek
I don't think this is right since you're looking for where the direction is at an angle of 45. Your method will give you where the x coordinate is equal to the y-coordinate but that isn't necessarily where the direction is at a 45 degree angle.


But it says 45 degree angle to both Ox and Oy where O is the origin, so would that not just mean along the line y=x or am I just adding to the confusion? :hmmmm:
Reply 7
Avatar for Notnek
Notnek
21
Original post by KaylaB
But it says 45 degree angle to both Ox and Oy where O is the origin, so would that not just mean along the line y=x or am I just adding to the confusion? :hmmmm:

The cartesian equation is the path of the particle, it doesn't show you the velocity.

So the particle is going to follow this parabola path. The direction of the particle will be the gradient of this parabola.

y = x on this parabola isn't the point where the gradient is at a 45 degree angle.

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you