Physics Alternating Current Level: University
Transmission of CurrentAn ac generator produces 10 A of current at 400 V. The voltager is stepped up to 4500 V by an ideal transformer and transmitted a long distance through a power line of total resistance 30.
(a) How much power is lost in transformer?
(b)If the voltage were not stepped up how much power would be lost in transmission?
(c) From your answer above is it more advantageous to transmit power at high or low voltage? Explain why?
(d) Why would a transformer not work if the current was direct instead of alternating? Explain fully.
Physics Alternating Current Level: University
TransformerPaul is experimenting with his new magic set. He has a thin insulated copper rod 1.0 m long with a mass of 50g. What minimum current must he put through the rod cause it to
(a) Float (=zero velocity) in a magnetic field of 1.0 T
(b) Accelerate upwards at 75 cm/s^2 in a magnetic field of 1.0 T.
(c) Is your answer to (a) greater than less than or the same as your answer to (b) ? Explain why.
(d) Suppose he wants to construct a 2.5 mT solenoid for other magnetic tricks. What length of wore would he need for a 10 cm diameter 20 cm long solenoid if he used a 100 mA current? Assume a constant diameter for each turn of the solenoid.
Physics Misc Topic Level: University
AstrophysicsIn 1054 AD chinese astronomers noted the appearance of a guest star that is a previously unseen star in the sky that then over time dimmed in brightness. Today we know that even as the supernova that created the crab Nebula.
(a) If the original star was 5.55 x 10^16 km away how many years ago did the star really explode?
(b) If astronomers used detectors to look for light from sodium with a frequency of 5.09 x 10^14 Hz what is the wavelength in nm of the light?
(c)One of the ways that astronomers look for evidence of extraterrestrial life is to look for signals at the radio wavelength of 21.0cm. Find the frequency of this radiation in Hz.
Physics Rotational Mechanics Level: University
TorqueA string is wrapped around a thin cylinder of radius R and mass M.A force F is applied to the end of the string and it unwinds.
(a) What is the angular acceleration of the cylinder?
(b) How many revolutions are mode by the cylinder in a time T?
Question Diagram
Physics Work,Power & Energy Level: University
Conservation of EnergyA thin hoop of radius R rolls without slipping on an incline which makes an angle theta relative to the horizontal. If the hoop is initially at rest what is the velocity after it has rolled a distance d along the incline.
Question Diagram
Physics Gravitation Level: University
Planetory MotionA plnet moves in an ell ptical orbit about a star under the action of gravitational force.
(a) List the conserved quantities for this system.
(b) Suppose the closest approach the planet makes to the star occur at A a distance 10^7 m and the father most approach occurs at B a distance of 3 x 10^7 m. If the planets speed at A is 10^4 m/s, What is its velocity at B?
(c) Which of the conserved quantities listed in part (a) can you calculate numerically with the intormation given in part (b) ?
Question Diagram
Physics Force & Laws Of Motion Level: University
Spring ForceSimple harmonic Motion
The force produced by a spring of spring constant k at displacement x can be expressed as?
Physics Properties Of Matter Level: University
Reflection of WaveWave phenomena
Consider waves incident on an obstacle. There will be a significant shadow region if:
(a) Wavelength>> objest size
(b)Wavelength equal to object size
(c) Wavelength << object size
Physics Properties Of Matter Level: University
Mode of VibrationVibrating Air Columns
Consider a closed 30.0cm long organ pipe. What is the frequency of the 2nd overtone when the speed of sound is 336m/s?
Physics Force & Laws Of Motion Level: University
Circular Motion DynamidsFind the centripetal force of a 10-kg mass traveling at 4.0 m/s on a curve radius of 3.0 m.
Physics Gravitation Level: University
GravitationFind the weight of a 5.5 slug safe.
Physics Work,Power & Energy Level: University
Find the kinetic energy of a 75-kg car that traveled 800 m in 50 seconds.( i used KE = 1/2 mxspeed to the 2 power)
Physics Heat & Thermodynamics Level: University
Charle's LawFind the original temp of a gas in degrees CELSIUS if the gas was moveed from a 75 cubic centimeter tank to a 225 cubic centimeter tank with a temperature of 123 degrees Celsius.
Physics Heat & Thermodynamics Level: University
ExpansionAt 20.0 degrees celius a copper disk is 10.00cm in diameter and a hole in the disk is 0.4000 cm in diameter. What are the diameters of the disk and the hole at 200 degress celius? The coefficient of the linear expansion of copper is 1.70 x 10^-5/ ( degrees celius)
Physics Heat & Thermodynamics Level: University
GasA gas contains molecules made with two different atoms. Measurements of the specific heat give results as stated. From T(sub-1) to T (sub-2) Cv/R = 1.5 from Describe the value of the three different results for Cv in the given temperature ranges as well as you are able to.
