thanks. your instructions are pretty clear
Originally posted by crimson soldier:Well TS, it seems that I made a mistake for part C. I used the formula for circular motion directly without realising that only the tangential acceleration = v^2/r. And to find tangential acceleration is pretty tedious in this case. But it can be done.
Alternatively
a) You want to find the radius of curvature.
b) You know that the radius vector is perpendicular to the vector of the velocity.
so
1) Find the velocity vector in terms of magnitude and direction. Magnitude given by sqrt( vx^2 + vy^2). Angle(direction) given by arctan(vy/vx).
2) Find the direction perpendicular to the velocity vector. It actually gives you the direction of the radius vector.
3) So you need to find the magnitude of the radius vector. Simple. You now have the angle and the horizontal distance of P from the origin (your x value basically).
4) Construct the basic right angled triangle and use cosine to find the magnitude of the radius.
A bit busy with my exams preparation or I would try to upload a peekture. It's probably university first year question.. either that or I'm trying too hard.
ok... im having problems already :s
@ Part 4)
not sure how it looks like or what values to use
hope this is not terribly urgent. I'm in no mood to draw diagrams haha
ha ha no not that urgent (y). tonight?
nup.. keep getting different answers :s
http://img17.imageshack.us/img17/903/physicsf.jpg
On a macbook using safari web browser. cannot do proper linking haha
Are you sure? i tried this:
180 - v angle - a angle = angle between a and v
where v angle is arctan (Vy/Vx) and a angle is arctan (Ay/Ax)
that gave me 72.78.
90 - 72.28 = 17.22 (became our theta for An)
32.54 cos 17.22 = 31.08 (our An)
4118.96 / 31.08 = 132.5 mm for R
on the top right u used arctan (Vx/Vy)?? i thought its the other way around
whats an? where's 4118.97 and 32.54 from?
Originally posted by crimson soldier:whats an? where's 4118.97 and 32.54 from?
32.54 is the magnitude of acceleration
4118.97 is the "V^2" in the a = V^2 / R equation
An is 31.08 (i think)
ok i see what u mean. i did the calculations and got 31.08 too.
something must be wrong with one of the two methods...should get same answer
Originally posted by crimson soldier:ok i see what u mean. i did the calculations and got 31.08 too.
something must be wrong with one of the two methods...should get same answer
looking at your picture, why did u use arctan (Vx/Vy)?
hmm like i said in first page, im assuming that the velocity vector is always perpendicular to the radius vector...
Originally posted by crimson soldier:hmm like i said in first page, im assuming that the velocity vector is always perpendicular to the radius vector...
thats also where i used the 90 in here:
90 - 72.28 = 17.22 (became our theta for An)
is that correct?
something like that lah