Physics - July 2007

A tri-cycle is at rest and the pedal is attached by a string. You pull the string with force F.
What does it do? and why? There is 4 reasons (concepts to the why question) so can anyone help me?

2007-07-17 11:05:16 · 5 answers · asked by rick m 1

2007-07-17 10:59:11 · 5 answers · asked by CRAZYGIRL 4

Please answer as SIMPLEST as possible!

2007-07-17 10:28:10 · 2 answers · asked by Anonymous

What is the practical purpose of vectors within crystal unit cells? What information do they provide and how is the formula writtien for them? Do vectors alo relate to moving from one unit cell to another? I am new to this stuff so basic responses would be appreciated.

2007-07-17 10:22:59 · 2 answers · asked by Gideon 1

i'm no expert on string theory, but as far as i know strings are made from energy. well, assume all the energy in a given object was somehow removed. perhaps by reaching absolute zero, would that object disappear?

2007-07-17 10:04:00 · 3 answers · asked by marcin p 1

My cousin recently took a test, and her answers seem correct to me but she was still marked off, can you guys help out?

A physics book is moving across a table. Can the book have a constant speed and a changing velocity? What about a constant velocity and a changing speed? Explain your answers.

2007-07-17 09:52:59 · 7 answers · asked by siiimonnn 2

Please explain it as simple as possible. No stupid answers please!

2007-07-17 09:47:15 · 3 answers · asked by Anonymous

Please let me know if the following is correct, or where I am making invalid assumptions:

1. Larger (by piston volume) piston engines are always less fuel efficient than smaller engines of the same design.

2. The reason larger piston engines are less efficient is that larger pistons (and related mechanisms) sweep larger surface areas and therefore have higher friction loses throughout their cycle.

3. For a given piston volume forced induction will always provide more power per unit volume, all else held constant.

4. Therefore, forced induction engines can always be more fuel efficient than naturally-aspirated engines that are capable of the same power levels.

2007-07-17 09:36:42 · 3 answers · asked by David B 2

if we hear sounds when our eardrums vibrate and the bones inside etc, how can we hear multiple sounds at once? wouldnt there just be interference as the vibrations all combine and muddle it up

2007-07-17 09:13:38 · 3 answers · asked by Michael N 2

I mean, some of those tunnels in NYC are like many many stories below ground.

This is also assuming the initial blast wasnt directly in the city, so fallen buildings and fire storms arent a major concern.

Would you be protected from the radiation and fall out. nevermind food or water.

2007-07-17 09:05:52 · 2 answers · asked by amosunknown 7

In a hydraulic lift, the diameters of the pistons are 4.96 cm and 20.2 cm. A car weighing W = 10.4 kN is to be lifted by the force of the large piston. (a) What force Fa must be applied to the small piston? (b) When the small piston is pushed in by 10.4 cm, how far is the car lifted? (c) Find the mechanical advantage of the lift, which is the ratio W/Fa.


Any help would be appreciated... I'm just looking to understand the problem!

2007-07-17 08:40:26 · 3 answers · asked by Kelly 1

2007-07-17 08:18:11 · 10 answers · asked by Anonymous

The pressure inside a bottle of champagne is 4.5 atm higher than the air pressure outside. The neck of the bottle has an inner radius of 1.1 cm. What is the frictional force on the cork due to the neck of the bottle?

2007-07-17 08:15:52 · 5 answers · asked by Anonymous

stationary ?

2007-07-17 07:36:26 · 14 answers · asked by ronaldmallier 1

2007-07-17 07:14:54 · 9 answers · asked by Devil 4

a railroad car of mass 2.5 times 10^4 kg is moving with speed of 4.00 m/s. it collides and couples with three other coupled railroad cars, each of the same mass as the single car and moving in the same direction with initial speed of 2 m/s.
How much mechanical energy is lost in the collision?

2007-07-17 06:45:05 · 4 answers · asked by animelover 2

why is it so that in refr. through glass slab the ray bends as soon as it enters glass and again when it goes out but in lens it bends only at optical centre?

2007-07-17 06:39:48 · 5 answers · asked by Anonymous

please i need some help quickly ! by the end of today .
does the air on the top of the wing go faster then the air under the wing ? or can you just tell about lift on a plane something i would understand at myage (14). as we have to show the class 2moro. :(:(:(

2007-07-17 06:38:34 · 6 answers · asked by Anonymous

and are there ways to make them more efficent

2007-07-17 06:28:13 · 1 answers · asked by macgyver 1

1-An archer shoots an arrow into a piece of wood. The arrow is traveling at 120 km/h when it strikes the wood. The arrow penetrates 3.8 cm into the wood before stopping. What is its average acceleration in meters per second into the wood?
2-It takes 4.20 s for a ball that was thrown down from the top of a building to reach the sidewalk below. The balls velocity upon striking the sidewalk is 148 mi/h.
a- How tall is the building?
b- What is the initial velocity of the ball?
3-A dragster runs the quarter mile in 8.96 s.
a- What is the cars velocity at the finish line in ft/s and in mi/h?
b- What is the cars average acceleration in ft/s squared?
4- A bullet is fired vertically upward from a gun with an initial velocity of 225 m/s.
a-how high does the bullet go?
b-how long does it take to reach its maximum height?
c-how long is it in flight?

2007-07-17 06:28:05 · 3 answers · asked by Anonymous

if the current in the cirucit is lower does this mean that the bulb will be dimmer and vica vera?

2007-07-17 05:48:57 · 6 answers · asked by Anonymous

Is there a limit on how advanced technology can get?

2007-07-17 05:29:47 · 4 answers · asked by Anonymous

I read somewhere about an experiment where a deep shaft was excavated and a caesium clock was placed at the bottom, with an identical one at sea level. The two clocks were calibrated to the same time at the start of the experiment, and the one at the bottom of the shaft was subsequently discovered to be running at a different rate to the one at sea level (sorry if I have got this wrong - it's been a while since I read this..). Is this a case of gravity actually affecting time itself, or merely the effect of gravity on the caesium atoms used in the clock - analagous to the timekeeping of a mechanical clock being affected by its proximity to a magnetic field. Sorry if this is a stuipid question!

2007-07-17 05:19:52 · 10 answers · asked by Anonymous

At time ti, the kinetic energy of a particle is 30.0 J and the potential energy of the system to which it belongs is 10.0 J. At some later time tf, the kinetic energy of the particle is 18.0 J. (a) If only conservative forces act on the particle, what are the potential energy and the total energy at time tf? (b) If the potential energy of the system at time tf is 5.00 J, are there any nonconservative forces acting on the particle? Explain.

2007-07-17 05:18:32 · 1 answers · asked by Anonymous

related to physics

2007-07-17 05:00:54 · 3 answers · asked by ayesha 1

The second identical cannon ball was dropped
from the tower with zero initial speed.

Which cannon ball will hit the ground first?
Please, do not ignore air resistance.

2007-07-17 04:49:13 · 11 answers · asked by Alexander 6

2007-07-17 04:26:30 · 4 answers · asked by Anonymous

2007-07-17 04:09:21 · 3 answers · asked by christian h 1

i need all info anyone can provide about quantum mechanics!!! May your provide links to sites for quantum mechanics research news, or links to universities where there might be some info published, or Information about international magazines that someone can pay and keep receiving them every month, and other stuff like that.

thnx a lot for any help!

2007-07-17 04:03:06 · 2 answers · asked by zweistein 2

If we are to believe that our known universe started as a singularity - a point of zero dimension and infinite mass, is it the case that all the matter that surrounds us actually has no volume and that the particles that we observe at the sub atomic level are ultimately composed of nothing more than energy?

2007-07-17 03:43:25 · 9 answers · asked by Anonymous