3U Maths Question Thread

[legorgo18]

RuiAce how do i solve the question with the piecewise function to get 8.1g i got confused

Btw just a general question how do you describe a motion when given v and a and also how do you know if a motion has changed direction or not when given a graph. Thanks!

[RuiAce]

You need to consider the maximum for the first component, and the maximum for the second component separately. Please post your graph and any working out you have. (The graph can be rough.)

v>0: moving to the right
v=0: at rest
v<0: moving to the left

a>0: accelerating to the right
a=0: not accelerating. Constant velocity.
a<0: accelerating to the left


Your graph could be the displacement, velocity or acceleration graph. Which are you given?

[legorgo18]

It is a velocity time graph starting from rest at the origin, max at t=1 and goes back down at t=2 like a bell shape. (sorry i tried taking a photo but when i upload it says i have exceeded file size)

[anotherworld2b]

Oh okay
I was also wondering how to do this question

[kiwiberry]

Oh okay
I was also wondering how to do this question

Use \(m=\tan{\theta}\) to find the gradient, and then sub the point into y=mx+b to find the eqn

[RuiAce]

It is a velocity time graph starting from rest at the origin, max at t=1 and goes back down at t=2 like a bell shape. (sorry i tried taking a photo but when i upload it says i have exceeded file size)

So now that I'm home, and have access to Desmos and other tools:

Larger

It would seem that the maximum occurs not AT t=1. Find where the parabola IS indeed maximised

Let's just bump the function I instructed you to graph.

Shit. Sorry about the typo.

[legorgo18]

oh no ruiace i was talking about the direction of the velocity graph not the piecewise function sorry

[RuiAce]

I already gave you the tools, so what graph are you considering?

If you're given the velocity graph, well just look at where it's above or below the t-axis.

If you're given the displacement, look at if it's increasing or decreasing. etc.

[legorgo18]

so if the velocity curve is always above t axis, there is no change in direction right? Sorry i kind of got confused

[RuiAce]

so if the velocity curve is always above t axis, there is no change in direction right? Sorry i kind of got confused

Yes that's true.

Because if the velocity curve is always above the t-axis, then we know that v>0 always. That means the particle is always moving to the right.

[legorgo18]

Thank you so much, sorry for the amount of question. The physics theory in this topic is kind of confusing.

[armtistic]

Hi guys, I always get stuck when it comes to loci questions for parametrics.
Generally, I'm fine for like "find the locus of the midpoint" sorts but I struggle when it comes to "describe the locus of A when B moves according to x-y=1" and such i.e. when there are two moving elements or something.

Any help would be appreciated. 

Edit: For 11, I've already gotten parts a) and b)

[RuiAce]

Hi guys, I always get stuck when it comes to loci questions for parametrics.
Generally, I'm fine for like "find the locus of the midpoint" sorts but I struggle when it comes to "describe the locus of A when B moves according to x-y=1" and such i.e. when there are two moving elements or something.

Any help would be appreciated. 

[RuiAce]

[VydekiE]

Hi,
Can someone please help me with this Probability question?
1. Two girls, Jan and Alison, throw two dice each. If Jan scores a total of 10, what is the probability that Alison will score higher?
Thank you!!