Recent content by pberardi

Thanks. Just curious. Since the kinematics do not apply, what would we do if we were given an initial velocity and an initial position?

I do not know any other formulas that give me a position. Could you give me a little bigger hint?

But I have already done the calculus. I am just using the v and a that I had before and just plugging them in. I really don't understand why this doesn't work.

Great thanks. But now I am having a bit of trouble with the position. It is asking me for the vector here so I split it up into components. For x I get xf = xi + vxit + 1/2(ax)t^2 which is xf = 0 + 4t(t) + (1/2)4t^2 at t = 3 gives 54 For y I get yf = yi +vyit + 1/2(ay)t^2 which is yf = 0 +...

Ok tell me if this will work: F = ma so a = F/m so a = <4, -2t>. v = <4t, -t^2> but speed is the mag of velocity so 15 = sq(16t^2 + t^4). So 225 = 16t^2 + t^4 which gives me four roots one of them being 3. Is this good?

What I did was integrate the force vector to get <8t, -2t^2> = 2a but I still have two unknowns.

Homework Statement A time-dependent force, F = 8i – 4tj N, is exerted on a 2.00 kg object initially at rest. a) At what time will the object be moving with a speed of 15 m/s? b) How far is the object from its initial position when its speed is 15 m/s? c) Through what total displacement has the...

I'm sorry I just don't get this. I do understand part c, but how to get part a and b in terms of kinematics and vectors is just too confusing for me to understand right now. I don't know why the answer .42 is incorrect. Can you try to explain it?

How do I get the acceleration? I would normally differentiate but I don't see how in this problem. Sorry for the bother.

What about the speed? The answer .42 is incorrect. Did I calculate correctly?

Homework Statement Heather in her Corvette accelerates at the rate of <3.20, -2.00>m/s^2, while Jill in her Jaguar accelerates at <1.00, 3.20>m/s^2. They both start from rest at the origin of an xy coordinate system. After 5.50 s, (a) what is Heather's speed with respect to Jill, (b) how...

Homework Statement Help with projectile motion please? A particle is at an elevation of 1.02m from the floor when it takes off. It reaches a max height of 1.85m above the floor and stops at .930m above the floor. How do you find the time of flight, the take off angle, the initial vertical...

Thank you sir.

Should be 0 = 24 + 36t + .5(-9.8)t^2 t = 7.96 ?

I am sorry, my mistake. I did do the calculus. But I wrote the height function incorrectly. It is supposed to be h = 3t^3 So based on this new information, is it correct?