Centripetal force

A device for training astronauts is designed to rotate the trainee in a horizontal circle of radius 10.8 m. If the force felt by the trainee is 7.30 times her own weight how fast is she rotating? I started with a=v2/R but can go no further. Where do I go from here?

Physics problem

A potter's wheel -- a thick stone disk of radius 0.500 m and mass 100 kg -- is freely rotating at 50.0 rev/min. The potter can stop the wheel in 6.00 s by pressing a wet rag against the rim and exerting a radially inward force of 65.0 N. Find the effective coefficient of kinetic friction between the wheel and the rag.

Torque and angular acceleration

Find the mass of a uniform solid cylinder which is mounted so that it can rotate freely (i.e., without friction) about a fixed axis that passes through its center and runs along the length of the cylinder. This is not a simple project because for one thing, that cylinder is heavy! Also you don't want to risk removing the heavy c ...continues

SOME USEFUL TIPS ON x RAY PRODUCTION

These are some tips to remember the following easily wavelength of X-rays produced and the dependence of wavelength and energy on the accelerating potential etc.

Modern Physics

1. Estimate how many heartbeats the average human experiences in a lifetime. Your answer should have no more than 1 or 2 significant figures. 2. Convert 65 mph to feet per second and to km/h. 3. Convert 88 ft/s to mph and to km/h. 4. The diameter of the sun is 1.39 x 10^9 m, and it is 1.5 x 10^11 m from the earth. Wh ...continues

need some help on a take home assignment to

I just took the first test of the semester and made a 52%. The class average was 57% so, I guess I left plenty of room for improvement. The professor gave us some x-credit to do for the purpose of raising exam scores. The x-credit is to take all the questions marked wrong and correct with an explanation of why your answer wa ...continues

Laws/3/4

Circular motion is often described as revolutions per second called: (a) period (b) frequency (c) amplitude (d) decibel The time required for one complete revolution of an object revolving in a circle is called: (a) period (b) frequency (c) time (d) amplitude Every particle in the universe attracts every ...continues

Force 5/6

1. The study of forces in equilibrium is called: (a) statics (b) traction (c) medium (d) angular velocity 2. The first condition for equilibrium: the sum of all forces is: (a) 100 (b) 50 (c) 1 (d) 0 3. The second condition for equilibrium, the sum of all lS zero. (a) forces (b) torque (c) momentum ...continues

heat/solid/gas/7

The Greek word for "moving" is: (a) kinetic (b) atom (c) potential (d) force If two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. This postulate is called: (a) first law of thermodynamics (b) second law of thermodynamics (c) third law of thermodyna ...continues

Force - An elevator is moving downward

An elevator is moving downward with an acceleration of 2m/s^2. What is the force exerted on the elvator floor by a person who weighs 75 kg?