HELP please!!!!!

apsara123 · 2016-09-10 03:18:33

My teacher assigned this homework called marble slide parabolas and I need to make it up to slide 16 but it's way too hard and I'm dying trying to figure it out.
Here's the link :
https://teacher.desmos.com/marbleslides-parabolas

Go there create a class code and try the problems...it's really hard. Can someone please give me the equation for all the slides from 4-16. THANK YOU so much!!!

bobbym · 2016-09-10 05:12:30

Hi;

I can not see the problems. Please post them here for help.

Bob · 2016-09-10 06:33:43

It looks like a coordinate grid with stars embedded. You can create a section of a parabola and place a marble at the top so it rolls down. Object to hit the stars. Seems to be a fun way to learn how the coefficients affect the shape of the parabola. At least that's what it seems like to me.

A screen shot of level 4 should be a good place to start.

If the section ends the marble can travel on being acted upon by 'gravity' so more stars may be hit even if they're not on the curve.

Bob

apsara123 · 2016-09-10 16:42:57

Here's the first 3 problems:
http://imgur.com/a/A2bJ8

i need an equation for each one so that it catches the stars. Thank you!!!

bobbym · 2016-09-10 18:46:50

Hi;

Is that the Desmos calculator? It is a nice calculator. The purpose of that seems to be make the parabola go through all the stars by experimenting with the equations given. You only have to change one character or so in the equations. How hard can that be? Did you try playing around a bit? For the first one I would start with the < and replace with +, -, etc and see what happens...

Bob · 2016-09-10 19:35:33

hi apsara123

OK, I've logged on and tried a few from the Student Preview. #1 was a demo. #2 was easy. #3 was just some instructions. #4 was a challenge but I got there eventually.

Where did you get your 1, 2 and 3 ? I'm not sure I'm seeing the same problems. If you post a picture for one you cannot do I'll try it.

LATER EDIT. Looks like I'm logged in as a teacher rather than a student. What class code are you using?

Bob

apsara123 · 2016-09-11 05:03:01

My class code is JB47 and i need help with everything from 2 to verify #4. Could you tell me the equations and i'll go check if it works and maybe alter it a bit if needed.

Bob · 2016-09-11 06:13:34

hi apsara123

Q2. The 'hint' here is not very helpful because the sign that needs to be changed isn't there. ??? eg. If I write 4, I mean +4 but usually we leave that sign out. So what is needed? If the parabola were up-side-down then the marble would roll around it hitting all the stars. So try making the whole expression negative.

Q4. I'll number the stars 1,2,3 and 4 from left to right. Note that 1 and 3 are at the same height. Parabolas have a line of symmetry so you need to stretch the whole parabola wider so that stars 1 and 3 are on the curve. Try varying that '2' at the beginning until star 1 is on the curve. Now try a launch and you'll find 1,2 and 3 are hit (but not yet star 4). The marbles have too much horizontal speed so they overshoot star 4. So change the ramp by changing {x<5}. I'll leave you to experiment.

Hopefully that's enough to get you going. Post back to say how you are getting on and if you get stuck again.

Bob

Math Is Fun Forum

#1 2016-09-10 03:18:33

HELP please!!!!!

#2 2016-09-10 05:12:30

Re: HELP please!!!!!

#3 2016-09-10 06:33:43

Re: HELP please!!!!!

#4 2016-09-10 16:42:57

Re: HELP please!!!!!

#5 2016-09-10 18:46:50

Re: HELP please!!!!!

#6 2016-09-10 19:35:33

Re: HELP please!!!!!

#7 2016-09-11 05:03:01

Re: HELP please!!!!!

#8 2016-09-11 06:13:34

Re: HELP please!!!!!

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