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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: filoballerx on March 03, 2011, 08:02:13 pm

Title: Physics
Post by: filoballerx on March 03, 2011, 08:02:13 pm

For what angle will the time travelled be the least?
For what angle will the horizontal speed be the fastest?

need help guys! and need some theories behind it

Title: Re: Physics
Post by: onur369 on March 03, 2011, 08:10:32 pm

Horizontal will be fastest at 45 degrees
and im guessing it will be slowest at 90 degrees

Title: Re: Physics
Post by: huaxiadragon on March 03, 2011, 08:12:23 pm

is this for inclined planes or for projectile motion?

Title: Re: Physics
Post by: filoballerx on March 03, 2011, 08:16:06 pm

well guys i found this experiement, this is the link http://seniorphysics.com/physics/rolling_ball.pdf

i jusst need back up theories because im making a report and i need theories for my introduction
by the way its for inclined planes.

Title: Re: Physics
Post by: filoballerx on March 03, 2011, 08:17:33 pm

or do you guys reckon i should just make that as my theory?

Title: Re: Physics
Post by: schnappy on March 03, 2011, 08:38:25 pm

If you're looking at rolling objects, you ahve to also consider anguler kinetic energy in addition to linear motion. If you neglect friction and air resistance, a block will fall quicker because it only has linear kinetic energy.

Your theory is meant to be your own theory... and tbh you're better to be wrong so you can discuss it more. It's a lot easier to discuss why you were erroreous than it is for you say 'I won bitches'.

If you want to legitmise your theory iwth maths or something, just draw the free body diagram(s) relevant. If you're going to go the easy route and intentionally be wrong, then just leave the important diagram out :)

Though I don't think this prac is a good one, it can be done using just maths (Something like finding friction coeffecients has to be done experimentally... tan(theta of inclination) = mu(s) for example is an easy one. If you do MM it should be a simple calc/trig problem for the fastest ([TH] represents theta, or the angle of inclination of the plane):
ma=mgsin([TH])
a=gsin([TH])
You want maximum a, use calculus to find the derivative and set it to 0:
a' = 10cos([TH])
0 = 10cos([TH])
[TH] = 90deg.

So it's fastest on a flat drop, no inclined plane. Process of horizontal speed is much the same.

Title: Re: Physics
Post by: Halil on March 03, 2011, 09:01:04 pm

I know that at 45 degrees a ball or object travels its max distance