Recent content by jcwhitts

I guess you can assume the final temperatures are equal. I think it was a problem with my signs in that I overcompensated for the fact that the coins lose heat, so they have a negative value for Q. The final temperature will obviously be less than 100 so I suppose that accounts for the sign change.

You can't assume the final temperatures are the same, sorry. So Qcoins=Qwater but (191*.003)(390)(R-100)=.275(4190)(T-17)

Homework Statement In a physics lab experiment a student immersed 191 one-cent coins (each having a mass of 3.00 g) in boiling water, at a temperature of 100 degrees C. After they reached thermal equilibrium, she fished them out and dropped them into an amount of water of mass 0.275 kg at a...

Figured it out. My approach went off on a tangent because the angular velocity is not constant. Instead, you use the energy approach K=1/2Iw^2 and know that the work is equal to the change in kinetic energy, and Power is work over time. So, Power * change in time =W. 1/2Iw^2=P*t, divide by...

As long as your first assumption is correct, that power times t is equal to the kinetic energy, you did the integration and the derivations correctly.

Any ideas?

Gyroscope-- Angular Speed, Rotational Kinematics, Precession Homework Statement A Gyro Stabilizer. The stabilizing gyroscope of a ship is a solid disk with a mass of 6.50×10^4 kg; its radius is 2.30m, and it rotates about a vertical axis with an angular speed of 500 rev/min. 1) How much...

Thanks a lot! I was making this question way too hard... I forgot how to solve simple systems of equations. I kept getting 0=0 because when I tried it before, I substituted the variable I solved for into the same equation rather than whichever I hadn't solved initially. Thanks again!

Vector Magnitudes given only direction--help! Homework Statement You leave your campsite to go get supplies at a store. You travel 230M at an angle 31 degrees south of east to get there(I'll call this vector A for simplicity's sake). On the way back to camp, you go a distance B at 43 degrees...