Physics - February 2007

Sound waves travel in water about four times their speed in air. When sound waves leave the air and enter the water, does their velocity change? Does their frequency change? Does their wavelength change? Please explain.

2007-02-20 14:27:25 · 2 answers · asked by anime_girl90 2

a basketball is thrown straight upward with an initial velocity of 3 meters per second. (a) by setting the motion equation equal to zero, find how long it takes for the basketball to stop moving upward. (b) use this time in the position equation to find the maximum height which the basketball reaches.

2007-02-20 14:25:41 · 3 answers · asked by judykharrison 1

ok I have recently watched a bunch of episodes of the new Doctor who show and have become interested in the concept of time travel. So I was wondering if anyone hapens to know any ideas or have any schematics they'd be willing to lend me. I would prefere one like the Delorian from back to the future or the armband from Timesplitters future perfect but anything would be good.

2007-02-20 14:23:13 · 11 answers · asked by Ryan H 2

The engineer applies the brakes, resulting in a net backward force of 1.87x10^6 N on the train. The brakes are held on for 33.0 s.

a)What is the final speed of the train? ___m/s

b)How far does the train travel during this period?_____m

need help on this one. thanks

2007-02-20 14:17:52 · 3 answers · asked by cosmo 1

2007-02-20 14:09:13 · 11 answers · asked by Anonymous

2007-02-20 14:07:39 · 12 answers · asked by Anonymous

Hi, I have a homework question from my acoustics class that I'm a little confused about:

Can air be a vibrating object with a natural resonant frequency? Explain.

This is the answer that I came up with: No, this is because a resonator requires a hollow body or cavity which allows for its vibration. Air in this case can only act as a medium transferring vibrations to the other vibrating system.

I'm not completely confident with my answer. Can anyone let me know if I'm on the right track? Thank you so much, I really appreciate the help!

2007-02-20 13:57:13 · 2 answers · asked by Enna 1

2007-02-20 13:57:06 · 7 answers · asked by watari777ph 1

2007-02-20 13:49:40 · 1 answers · asked by Buck BUCK 2

I just need to know what thermodynamics is for besides knowledge

2007-02-20 13:49:13 · 3 answers · asked by Anonymous

A harmonic wave is traveling along a rope. It is observed that the oscillator that generates the wave completes 40.0 vibrations in 30s. ALso, a given maximum travels 425cm along the rope in 10s. What is the wavelength?

2007-02-20 13:20:16 · 1 answers · asked by Kitana 2

The motion of an object is described by the equation
x=(0.3m) cos(Pit/3)

a. find the position of the object at t=0 and t=0.6s.
b. amplitude of the motion
c. frequency of the motion
d. the period of the motion

2007-02-20 13:15:33 · 1 answers · asked by Anaksonamun 2

A free electron and a free proton are placed in an identical electric field. Compare the electric force on each particle. How do their accelerations compare?

2007-02-20 13:13:55 · 2 answers · asked by socom_lover 2

2007-02-20 13:12:40 · 8 answers · asked by Shelby 2

In a portable oxygen system, the oxygen (O2) is contained in a cylinder whose volume is 0.0029 m3. A full cylinder has an absolute pressure of 1.3 107 Pa when the temperature is 298 K. Find the mass of oxygen in the cylinder.

2007-02-20 13:04:53 · 1 answers · asked by Anonymous

Two ideal gases have the same mass density and the same absolute pressure. One of the gases is helium (He), and its temperature is 173 K. The other gas is neon (Ne). What is the temperature of the neon?

2007-02-20 13:04:22 · 1 answers · asked by Anonymous

During an all-night cram session, a student heats up a (0.9 10-3 m3) glass (Pyrex) beaker of cold coffee. Initially, the temperature is 15°C, and the beaker is filled to the brim. A short time later when the student returns, the temperature has risen to 90°C. The coefficient of volume expansion of coffee is the same as that of water. How much coffee (in cubic meters) has spilled out of the beaker?

2007-02-20 13:03:38 · 2 answers · asked by Anonymous

a block that has a mass of 36 kg is initially at rest on an 20 degree inclined plane. (a) find the component of the weight that is parallel to the plane. (b) find the component of the weight that is perpendicular to the plane. (c) find the maximum force of static friction if the coefficient of static friction is .29 (d) find the acceleration of the block if the coefficient of kinetic friction is .18.

2007-02-20 12:51:31 · 2 answers · asked by argentina_mandy20 1

Hey yall! I need help with three physics questions. I hope you guys can help me!!! Thanks!!!!!!!!

1. The third floor of a house is 8 m above street level. How much work is needed to move a 150 kg refrigerator to the third floor?

2. Stan does 176 J of work lifting himself .300 m. What is Stan's mass?

3. Lee pushes a 20 kg mass 10 m across a floor with a horizontal force of 80 N. Calculate the amount of work Lee does.

2007-02-20 12:50:12 · 3 answers · asked by happygolucky! 1

The resistance distance is 4 meters and the resistance weighs 80 Newtons. The effort distace is 12 meters. How much effort force must be applied to lift the resistance?

2007-02-20 12:45:13 · 1 answers · asked by Anonymous

If two displacement vectors add to yield a total displacement of zero, what do you know about the two displacements?

2007-02-20 12:44:50 · 3 answers · asked by ~hobo~ 1

I have to submit the answer online..it's due in a few hours. This is the only problem I can't get...I don't even know how to begin to solve it. Any help would be appreciated.

By roughly how much does the mass of a copper object change when, upon being stroked with a piece of woolen cloth, it acquires an excess charge of -0.6 µC?

2007-02-20 12:39:06 · 2 answers · asked by oriolesfan2323 4

2007-02-20 12:23:21 · 7 answers · asked by Cass 1

The sides of a cone make an angle "THETA" with the vertical. A small mass "m" is placed on the inside of the cone and the cone, with its point down, is revolved at a frequency "f" about its symmetry axis. If the coefficient of static friction is "MU", at what positions on the cone can the mass be placed without sliding on the code? (Give the maximum and minimum distances, "r", from the axis)


I guess what it boils down to is what forces are acting on the mass... what am I missing. So far I have these forces:
Centripetal, friction, and gravity. Is that it? And is (f/(2*pi*r)) equal to velocity?

2007-02-20 12:10:26 · 2 answers · asked by Anonymous

Basically I need to know the probability of both incidents occurring.

2007-02-20 12:04:48 · 3 answers · asked by oi_son_of_sam_io 2

2007-02-20 12:01:10 · 1 answers · asked by dimondglove 4

Centripetal force comes from the movement of the object, or by gravity, but where does centrifugal force come from in satellite motion?

2007-02-20 11:47:49 · 3 answers · asked by thyplo101 2

and why?

2007-02-20 11:32:29 · 3 answers · asked by kp000000 1

2007-02-20 11:23:50 · 9 answers · asked by pole smokin pete 1

State the condirion that is necessary for a charge to move in a wire.

Explain how connecting an electric device to a battery produces a current in the device.

Relate the definition of electric current to the units of current.

Compare supercunductors and semiconductors with cunductors and insulators.

2007-02-20 11:22:34 · 1 answers · asked by Anonymous