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1. Center of Mass and Wedge

Homework Statement A large wedge rests on a horizontal frictionless surface. A block starts from rest and slides down the inclined surface of the wedge, which is rough. During the motion of the block, the center of mass of the block and wedge. a. does not move. b. moves horizontally with...
2. Thermodynamics heat engine Question

Homework Statement A 1500kW heat engine operates at 25% efficiency. The heat energy expelled at the low temperature is absorbed by a stream of water that enters the cooling coils at 20 degrees C. If 60L flows across the coils per second, determine the increase in temperature of the water...
3. Forces and Pulleys

Homework Statement A pulley has a moment of inertia of 5.0 kg*m^2 and a radius of 0.5m. The cord supporting the masses m_1 and m_2 does not slip, and the axle is frictionless. Find the acceleration of each mass when m_1 = 2.0 kg and m_2 = 5.0 kg. Homework Equations F=ma, Fr=I(alpha)...
4. Acceleration in respect to power, and a KE/momentum problem.

I was doing the IPhO F=ma test from 2008 and couldn't get these two questions. Question 1 Homework Statement A car has an engine which delivers a constant power. It accelerates from rest at time t = 0, and at t = t_0 its acceleration is a_0. What is its acceleration at t =2t_0? Ignore energy...
5. Deriving the Formula for Gravitational Potential Energy

Hey guys, Do any of you happen to know how to derive the formula for General gravitational potential energy (not the mgh one) without using calculus? Thanks. Just in case you guys want to know, I'm trying to derive the equation for this: http://xkcd.com/681_large/. I've got most of it, but I...
6. Xkcd (angular momentum problem)

I was reading xkcd and wondering if spinning in a counterclockwise way (on the northern hemisphere) would actually steal some of earth's angular momentum and slow it down a bit. Is it possible or does this violate conservation of momentum?
7. Are newton's three laws applicable everywhere?

Are newton's three laws applicable everywhere in the universe?
8. Black holes and space time

If black holes stretch the space-time fabric because of their mass existing in singularity, if you were near a black hole, wouldn't there be a time-stretch?
9. What is Bose Eintein Condensate?

I am doing a project on bose einstien condensate at school. Could someone please explain to me what it is in a easy to undertand way?I don't understand about the doppler shift part.:confused: