Recent content by doctorjuice

I've been taught the same definition, I was just asking why it was defined this way, I didn't see the reason for it at first. There are actually a couple reasons, I believe (and I would like to hear confirmation or refutal of these reasons): 1) If a x b = +/-c (instead of +c), then the...

First question: a x b = -b x a Why is this so? As I understand, a major purpose of the cross product (if not, the purpose) is to find a third vector that is perpendicular to two other vectors simultaneously. Let's say a x b = c. Shouldn't the answer really be, a x b = +/- c? Since, of...

Gravity would affect tension, right? If they say the tension is 15N at the bottom, aren't they including gravity?

Homework Statement 0.5kg ball swings in a vertical circle at the end of a 1.5m long string. When the ball is at the bottom of the circle the tension in the string is 15 N. What is the speed of the ball at that point? Homework Equations ac=T/m ac=v^2/r The Attempt at a Solution...

Homework Statement A 5000kg rocket is launched at 44.7º with a thrust of 140,700N. a. Find an equation y(x) that describes the rocket's trajectory. b. Shape of trajectory? c. At what elevation does the rocket reach the speed of sound, 330m/s? Homework Equations F=ma The distance...

Yes! I can't believe I didn't think of that. Thank you!

Homework Statement What is the impulse on a 3.0 particle that experiences the force shown in the figure (Figure 1) ? Figure 1: http://session.masteringphysics.com/problemAsset/1382988/2/09.EX04.jpg Homework Equations Impulse equations, force equations, how they relate. The...