Recent content by Nghi

AAAHHH I GOT IT I GOT IT! i forgot that the time for the stone b is 2.18 seconds less than stone a! yayyy!

i'm still stuck on what i need to do... i don't know where to go after finding the speed of the first stone at 2.18 seconds. i know a = 9.81 m/s^2, speed of the first stone is 21.3858 m/s when the second stone is thrown with an initial velocity of 31 m/s. after that, everything is coming up...

Homework Statement A stone is dropped from a cliff; 2.18 s later another stone is thrown downward with an initial speed of 31 m/s. They reach the ground simultaneously. Find the height of the cliff. Homework Equations vf^2 = vo^2 + 2ax x = vot + 0.5at^2 vf = vo + at The Attempt at...

Thank you so much! :)

Homework Statement A large punch bowl holds 3.95 kg of lemonade (which is essentially water) at 20 C. A 1.74 kg ice cube at -10.2 C is placed in the lemonade. What is the final temperature of the system, and the amount of ice (if any) remaining? Ignore any heat change with the bowl of...

Homework Statement Two wave pulses on a string approach one another at the time t = 0, as shown in the figure below, except that pulse 2 is inverted so that it is a downward deflection of the string rather than an upward deflection. Each pulse moves with a speed of 1.0 m/s. Assume that the...

asd;falsflasldf; I hate myself so much sometimes. :( But thank you so much for the help. Seriously. I was ready to punch myself in the eyeball from this problem.

Homework Statement The weight of your 1205 kg car is supported equally by its four tires, each inflated to a gauge pressure of 35.7 lb/in.^2. a) What is the area of contact each tire makes with the road? (in m^2) b) What gauge pressure is required to give an area of contact of 113 cm^2...

It's an online homework problem, so the answers won't be shown until tomorrow. I'm just frustrated that I'm going to get deducted for a problem that I know that I'm doing right. :( I just emailed my professor, asking him for clarification, so hopefully he'll reply soon. But thank you for...

Homework Statement A particular comet has an elliptical orbit. When closest to the Sun (perihelion) it is at a distance of 8.823 x 10^10 m and moves with a speed of 54.6 km/s. The greatest distance between this comet and the Sun (aphelion) is 5.902 x 10^12 m. Calculate its speed at...

I guess what I don't understand is WHEN to use center of mass. Is it used exclusively for gravitational PE? It just seems really random for the problem to pull out center of mass. There really isn't any specific problem in the book that I've encountered (sorry! :(), but it's just in general, I...

Ahh, that makes sense. So a few small after-questions, then: 1. does this center of mass come into play for objects that rotate? Because all of the other problems I've done concerning PE and KE didn't include center of mass as a factor. 2. If it was a rotating sphere instead of a stick...

Wait, I just reread what you wrote. If I'm suppoesd to follow its center of mass, and it's a uniform rod, does that mean the center of mass is located at the geometric center? And would that geometric center be located at the knees? Because if so, then that would make the height h = 0.83/2, or...

So the foot falls in a quarter of a circle instead. So... that mean I have to use C = 0.5(pi)r to find height h?

The KE I got is the equation used for rolling motion without slipping. But I guess that wouldn't make sense, since the leg isn't really doing any translational kinetic energy. But about the rotational energy thing: I also did that, I believe, and didn't get the right answer. :( initial PE +...