Physics - November 2007

what kind of motion do you expect to occur? Why? please help

2007-11-12 08:55:59 · 1 answers · asked by smarty 2

Two friends want to close their heavy door, but are too lazy to get up. They agree to throw an object at the door to close it. Ernie suggests throwing a 300 g lump of sticky clay at the door, but Bert argues that a 300 g tennis ball would work better if thrown at the same speed. Who is correct? Explain in detail, basing your explanation on fundamental physics principles.

2007-11-12 08:47:58 · 6 answers · asked by Anonymous

1)If the hanging mass is 100. g and drops a distance 25.5 cm in a time of 6.0 s, what is the moment of inertia of the support rod and shaft? The radius of the shaft is 0.50 cm.

2)Now two masses each of 180 g are placed on the rod at a distance of 15.0 cm from the point of rotation. What is the TOTAL moment of inertia of the masses plus rod and shaft?

3)How long does it take for the hanging mass to fall the same distance 25.5 cm?

please show work so I can understand the problem

2007-11-12 08:37:52 · 1 answers · asked by kiranrai98 1

2007-11-12 08:21:38 · 2 answers · asked by Maria C 1

A uniform thin rod of length 0.50 m and mass 3.5 kg can rotate in a horizontal plane about a vertical axis through its center. The rod is at rest when a 3.0 g bullet traveling in the rotation plane is fired into one end of the rod. As viewed from above, the bullet's path makes angle = 60° with the rod If the bullet lodges in the rod and the angular velocity of the rod is 14 rad/s immediately after the collision, what is the bullet's speed just before impact?
m/s

2007-11-12 07:48:18 · 2 answers · asked by Wonder 2

Find the second resonant length of an air column that resonates with a sound of frequency 1.0 kHz. at 15.0 degrees C under each of the following conditions:

a) The air column is closed at both ends.

b) The air column is open at both ends.

c) The air column is open at one end and closed at another.

2007-11-12 06:22:53 · 1 answers · asked by Anonymous

What is the density of nitrogen gas (molecular mass = 28 u) at a pressure of 2.3 atmospheres and a temperature of 282 K?

Ok so first I converted the molecular mass to moles, which would be 2, and then I used the equation pv=nrt to get the volume, and then divided the volume by the mass, and got an answer of 1.4 but that is wrong. Any idea of what I'm doing wrong?

I'd appreciate any help.

Thanks.

2007-11-12 05:43:26 · 2 answers · asked by Anonymous

http://i4.tinypic.com/6ut59xe.gif

Mechanical works done by the mechanic were respectively
A1 = +300J
A2 = +200J

What is spring constant K of the spring?

2007-11-12 05:37:49 · 2 answers · asked by Alexander 6

The cab starts moving with an accelartion of 1 m/s^2 and is 20 meters down the street from you. You have 50 meters to catch the cab and are able to run with a max. speed of 8 m/s. Will you catch the cab given these circumstances?

Best Answer to first correct answer!!

2007-11-12 05:32:01 · 1 answers · asked by Anonymous

2007-11-12 05:31:35 · 7 answers · asked by Anonymous

We know that frequency is the energy pulses of an emitter, which is pretty much every conceivable thing since everything in its deepest level is made of atoms and atoms are made of electrons and protons and neutrons - all of which are particles
made up of energy, electricity that is; and they vibrate and do
have a frequency therefore.
So in this order of thought, it turns out that frequency is a universal property of energy? and that every particle can be defined by its frequency (and the Universe and everything we know is an elegant symphony of vibration.:-)

2007-11-12 05:29:11 · 2 answers · asked by Ateviel 3

This is a model of a 'Swing Carousel' ride at a funfair. I have made for a physics project and I'm having awful trouble .. Thank you!

2007-11-12 05:26:18 · 1 answers · asked by charly.lizzy 2

I need help finding out what thermal energy is and I needs some examples of it.

2007-11-12 05:07:52 · 3 answers · asked by Sir Wolfex 1

Calculate the resonance frequency of a free electron in a magnetic field of 1 T. What is the associated wavelength?

2007-11-12 05:01:36 · 4 answers · asked by mark r 4

I've seen the subs, so I only want the dubs please.

2007-11-12 04:57:32 · 1 answers · asked by sangovengence 2

The inside diameters of the larger portions of the horizontal pipe in Figure P9.47 are 2.40 cm. Water flows to the right at a rate of 1.60 10-4 m3/s. Determine the inside diameter of the constriction.
http://www.webassign.net/sf/p9_47.gif

2007-11-12 04:55:28 · 1 answers · asked by Burton 1

1) What force is necessary to drag a 20N box up a 45 degrees incline plane if the coefficient of friction is .47?

I think I understand some of this. Ff= Coefficient of Friction x Fn.
Coefficient of Friction: .47
W: 20N
Fn=W times Cos)Theta.
Fn=20N times Cos)45= 14N
Ff= Coefficient of Friction x Fn
Ff= .46 x 14N= 6.6N

This is where I got lost. Any help please?

2) The coeffient of a Sliding friction between a crate and a horizontal floor is .27. If the crate has a mass of 250kg, what force is needed to slide it across the floor at constant velocity?

I think I got this one.
Coefficient of Friction= .27
M: 250kg
W: 250kg x Gravity(9.81)= 2453N
Ff= Coefficient of Friction x W
Ff=2453N x .27= 662N

Thanks alot for those who helps.

2007-11-12 04:43:56 · 3 answers · asked by Lying from you 4

during a baseball game, a batter hits a pop-up to a fielder 88 m away. the acceleration of gravity is 9.8m/s/s. if the ball remains in the air for 6.1seconds, how high does it rise? answer in units of meters.

2007-11-12 04:31:19 · 2 answers · asked by broncosfanatic09 1

2007-11-12 04:11:09 · 4 answers · asked by jason b 1

How long must the second hand of a watch be for the tip to be traveling faster than the speed of light?

2007-11-12 03:49:54 · 4 answers · asked by Susan R 1

a. their clock would be slower and their light red shifted

b. their clock would be slower and their light blue shifted

c. their clock would be faster and their light blue shifted

d. their clock would be faster and their light red shifted

2007-11-12 03:29:42 · 1 answers · asked by Jacquisha R 1

a girl coasts down a hill on a sled, reaching level ground at the bottom with a speed of 6.8 m/s. The coefficient of kinetic friction between the sled's runners and the hard, icy snow is 0.044, and the girl and sled together weigh 651 N. A=9.81 m/s^2.

a) How far does the sled travel on the level ground before coming to a rest?

b) What is the coefficient of kinetic friction b/w the block and the incline?

c) What is the magnitude of the frictional force acting on the block?

d) what is the speed of the block after it slides the distance of 2.67?

2007-11-12 03:19:53 · 1 answers · asked by ? 2

A phonograph record has an initial angular speed of 33 rev/min. The record slows to 10 rev/min in 1.7 s. What is the record's average angular acceleration during this time interval?

2007-11-12 02:47:54 · 2 answers · asked by Jon Johanson 1

I've often doubted Einstein when it comes to time dilation. The theory that time slows down the faster you travel.

The reason for my questioning is that all of the comments I've heard on the subject seem, to me, to suggest that clocks would slow down the faster they travelled.

None of the clocks I've seen measure time, the clocks count the number of oscillations or ticks, and knowing how long it normally takes to oscillate we can then work out the 'time'.

If that is the case, I can simply slow down time by 'rigging' a clock.

It doesn't mean that I've stopped or slowed down time - just the clock.

Am I incredibly wrong, or is there something to this?

2007-11-12 01:22:37 · 17 answers · asked by mark 7

water falling frm a 50 m high fall is used for generating electric energy.if 1.8*10^5 kg of water falls per hour and half the gravitational potiential energy can be converted into electric energy how many 100 w lamps can be lit????

2007-11-12 01:22:27 · 4 answers · asked by shreyas 2

http://class.phys.psu.edu/212Recitations/09_Induction/Faradays_Law.pdf

Need help with Q2 part

2007-11-12 01:18:03 · 2 answers · asked by Anonymous

Why do atoms have no electric charge even though most of their particles have charges? this another question i dont know pls help me

2007-11-12 00:54:42 · 8 answers · asked by Help!!! 1

2007-11-12 00:46:54 · 1 answers · asked by Anonymous

Now, obviously, I'm not talking about nuclear waste - just the stuff from landfills - "clean" garbage, as it were. Wouldn't dumping trash in a active volcano like Kilahuea cause it to burn up/melt and return those elements back to the Earth? As for the satellites that are useless and make up space junk that eventually fall to earth, couldn't we just give them a push toward the sun? Even if they were to hit Venus or Mercury, who cares? Serious, scientific, intelligent replies please, thanks!

2007-11-12 00:39:11 · 20 answers · asked by dtxn 1

You have two bars of metal placed upon a table, 10cms in length and 2cms square.They are identical in every aspect apart from the fact that one of them is a magnet.When they are moved close to each other they seem to attract each other. Without removing them from the table, and with no other aids, how do you tell which is the magnet

2007-11-12 00:37:52 · 4 answers · asked by Paddy 4