Physics questions

[TrueTears]

Thanks, but what's s? and how did you get the 2nd parametric equation?

[superflya]

u mean the s in s=ut +1/2at^2, displacement.

it has an initial acceleration and the forward thrusters are turned on after 3 seconds. so u get 2 equations.

[TrueTears]

but in my book it says "s is the generic axis"

what the f does that mean?

[/0]

Thanks, but what's s? and how did you get the 2nd parametric equation?

i was just quoting the standard kinematic equation... i guess 's' isn't that standard in vce. It's just position displacement*.

As for the second parametric equation, I simply split the motion of the shuttle up into x and y components. In the y-direction the shuttle will have a constant acceleration of , so the y-component remains the same for all time.

At 3 seconds it turns on the x-component boosters and gets an acceleration of .
However, since it only starts this at , we must use instead of so that at the x-displacement is zero.

[TrueTears]

ok thanks

what about this Q

can u show me how to do it? i have no idea.

[TrueTears]

what are inertial reference frames?

[superflya]

frames of reference where newtons laws of motion and the laws of inertia hold true.

http://cseligman.com/text/physics/inertial.htm

[TrueTears]

yeh i know, but why do they hold true?

what is the actual meaning of an inertial frame of reference, not the implications of it

[TrueTears]

what is angular velocity? i know its

but what does it mean? say i got a graph and its like the one attached, how do u describe the motion of the particle?

[TrueTears]

what is uniform circular motion? is that when the speed of the particle is constant? but doesnt have an acceleration of a = v^2/r so shouldn't it pick up speed?

[appianway]

Acceleration refers to change in velocity. Velocity is different from speed - velocity is a vector. So while the magnitude of the velocity (ie the speed) can be constant, the velocity must change when acceleration occurs.

Uniform circular motion refers to orbiting at a constant radius at a constant velocity.

[Twenty10]

no acceleration is a vector and therefore we take into account the direction its travelling. The magnitude of speed is the same but the direction is constantly changing and it is therefore accelerating.


ed: damn got beaten to it

[TrueTears]

Acceleration refers to change in velocity. Velocity is different from speed - velocity is a vector. So while the magnitude of the velocity (ie the speed) can be constant, the velocity must change when acceleration occurs.

Uniform circular motion refers to orbiting at a constant radius at a constant velocity.

o i see but if its at a constant velocity, doesn't that mean it has to point in the same direction, so how can it travel in a circle if the velocity is constant? wund't it be a line??

[TrueTears]

also for non uniform circular motion the acceleration doesn't point towards the centre of circular anymore right?

whats radial acceleration and tangential acceleration? i understand the magnitude of the acceleration in non uniform circular motion is given by , but where did this radial acceleration and tangential thingy pop up from?

[Twenty10]

velocity isnt constant. The direction changes. The magnitude of velocity (Speed) is constant.