Cost of operating a heating element

A heating element draws 7.50 A on a 120V line. At the rate of 8.00 cents per kW h what is the cost of operation for 5.00 h?

Wheatstone bridge

Use Wheatstone bridge to determine an unknown resistance

Lorentz transformation and the Doppler effect.

The radar speed trap operates on a frequency of 10^9 Hz. What is the beat frequency between the transmitted signal and one received after reflection from a car moving at 30 m/sec?

Gravitational attraction between an electron and a proton in a hydrogen atom. first Bohr orbit of a hydrogen atom.

The gravitational attraction between an electron and a proton in a hydrogen atom is weaker than the coulomb attraction by a factor of about 10-40. An alternative way of looking at this fact is to estimate the radius of the first Bohr orbit of a hydrogen atom if the electron and proton were bound only by gravitational attraction. ...continues

Comparing Earth's g value to Mars.

Mars has a mass of 6.37x10^23 kg and a radius of 3.43x 10^6. What is its "g" value compared to that of earth?

Calculating sound waves, wavelength shift in regards to the Doppler Effect.

A sound detector is placed on a railway platform. A train, approaching the platform at a speed of 36km/h sounds its whistle. The detector detects 12 kHz as the most dominant frequency in the whistle. If the train stops at the platform and sounds the whistle, what would be the most dominant frequency detected? The speed of sound ...continues

Sample problem on instantaneous velocity.

The position of a particle moving on an x axis is given by: x=7.8 + 9.2t - 2.1t^3 with x in meters and t in seconds. What is its velocity at t=3.5s? Is velocity constant or changing?

mechanics

1)a.A grind stone of 0.1m thick,1m of diameter and a relative density of 2.53 find-moment of inertia+ radius of gyration. b)A gun is fired at a target 12km away at an angle of 35deg and hits target.How long is the projectile in the air and what's it's velocity? need complete step by step answer,t ...continues

Working with vector magnitude and direction.

Given 2 vectors V1=(6,8) and V2=(-11,4) find the magnitude and direction of V1 + V2 and V1 - 2V2

Working with velocity, distance and time.

It takes 4 years to reach the nearest star. The speed of light is c=3.00x10^8m/s. How many kilometers away is the star?