Physics - October 2007

Two trains, one travelling at 100 km/h and the other at 128 km/h are headed towards one another along a straight level track. When the trains are 1.2 km apart, each engineer simultaneously sees the other's train and applies the brakes. Both trains have equal, constant decelerations of 0.9 m/s^2. Will there be collision?

can i please see the steps involved in solving this problem? Thank uu

2007-10-17 09:46:12 · 1 answers · asked by cool 3

Use the mass of the sun and its distance to the Earth to compute the time it takes the earth to circle the sun? Express your answer in years.

What equation do I use to slolve this and what is the answer. I think I did it incorrectly. Not sure if the answer is one year.

2007-10-17 09:42:49 · 1 answers · asked by Anonymous

I have the answer to this question but i don't know how it was reached. A woman pushes two crates, weighing 4kg and 20kg, across a frictionless floor. The crates are next to and touching each other. If she exerts a force of 36 N on the smaller crate, approximately what force does the smaller crate exert on the larger crate. the options are 36N, 30N, 200N, or 240 N. 30 is the correct answer. i'm having trouble drawing a freebody diagram for this problem. thanks

2007-10-17 09:31:31 · 1 answers · asked by Anonymous

two forces F1 and F2 are acting horizontally on a spool at radius 2r and r respectively show that inorder to have zero friction force at the bottom the ratio F1/F2= ( I+2mr^2)/(4mr^2-I)
where I is the moment of inertia of spool and m is the mass.

2007-10-17 08:32:23 · 1 answers · asked by sameerteacher01 1

2007-10-17 07:46:57 · 6 answers · asked by Grinning Football plinny younger 7

Just seen this U tube;

http://www.youtube.com/watch?v=K70JzbIgVIE

Can someone explain it? The energy used in the heat given off is obviously from the batteries, but what are the chemical mechanics?
.

2007-10-17 07:30:53 · 10 answers · asked by John Sol 4

This question is for the physics gurus, or just anyone who understand general physics better than I.
Here is a link to the diagram I will be refering to
http://i1.pinkbike.com/photo/1311/pbpic1311021.jpg
The 50 lbs to compress bit is very flexible, basically im looking for a range between 25-50lbs, no more than or less than that range however. This is a project I am having to delay because of not having the correct spring - and I know one exists! I just dont feel like quessing and checking without having a starting point.

physical limitations for the spring:
-Must fit in the 1" chamber, preferably a sixteenth or so smaller for squirm room.
-must fit around a 7/16" rod
-Compressed length must be around 1"
-Extended length can be w/e is neccesary to meet the requirements.

Sorry for the detailed post, as you can tell I pretty much know what i'm doing, just havent made it all the way through general physics yet and my mechanical skills are ahead of my physics skills

2007-10-17 06:50:08 · 1 answers · asked by Steve W 2

An athlete executing a long jump leaves the ground at a 30 degree angle and travels 7.80 m. What was the takeoff speed? If this speed were increased by just 5.0 percent, how much longer would the jump be? Please show/explain all work clearly.

2007-10-17 06:28:30 · 1 answers · asked by nirmal 1

A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale breifly reads only 0.75 of the person's regular weight. Calculate teh acceleration of the elevator, and find the direction of acceleration.

2007-10-17 06:27:45 · 2 answers · asked by LabStudent0 1

If I have negative velocity and I want to solve momentum question do I have to write negative sign of velocity in momentum formula or not like
V1M1+V1M2=V2M1+V2M2

2007-10-17 06:02:30 · 2 answers · asked by M R 1

to practice for the test!

2007-10-17 05:57:42 · 1 answers · asked by Sara *Life is so unlike theory* 5

2007-10-17 05:46:44 · 7 answers · asked by justina k 1

Why is the electric field between parallel plates uniform?
Appreciate the help :)

2007-10-17 05:38:49 · 4 answers · asked by Hannah 4

2007-10-17 05:31:47 · 5 answers · asked by Anonymous

2007-10-17 05:15:23 · 3 answers · asked by Anonymous

2007-10-17 05:07:17 · 5 answers · asked by Anonymous

2007-10-17 04:51:49 · 4 answers · asked by Anonymous

3) Styrofoam is a polymer containing carbon and hydrogen. Assume the formula is C8H8. How many molecules are in a 0.2 g styrofoam peanut? How many protons and electrons are in this peanut if it carries no excess charges? How many coulombs of positive and negative charge does this represent? If the peanut has an excess charge of 0.05C, how many of its electrons has it gained or lost?

2007-10-17 04:47:57 · 1 answers · asked by sdajc0603 2

2007-10-17 04:24:31 · 4 answers · asked by Anonymous

Why are these forces often called fundamental or basic forces?

Where are these forces found?

How are other forces related to them?

2007-10-17 04:22:35 · 2 answers · asked by Anonymous

2007-10-17 04:07:57 · 5 answers · asked by princes3242000 1

To appreciate the forces that a fighter pilot must endure, consider the magnitude of Fn of the normal force that the pilot's seat exerts on him at the bottom of a dive. The magnitude of a pilot's weight is W. The plane is travelling at 230 m/s on a vertial circle of radius 690 m. Determine the ratio Fn/W.

2007-10-17 03:55:32 · 4 answers · asked by Anonymous

I want to know the concept of resistivity and also that what is the difference between resitance and restivity.

2007-10-17 03:34:33 · 13 answers · asked by Space Crazy 2

2007-10-17 03:28:53 · 3 answers · asked by Space Crazy 2

a boy wearing a white t-shirt and has a yellow duck sitting on a blue boat printed on it. he goes inside a room with red lights. which color will his t-shirt, duck and the blue boat look.????//

2007-10-17 01:51:17 · 5 answers · asked by Crab! 2

Two identical loudspeakers are driven by the same oscillator of frequency 200Hz. The speakers are located on a vertical pole a distance of 4.00m from each other. A man walks straight toward the lower speaker in a direction perpendicular to the pole.

a) How many times will he hear a minimum in sound intensity?

b) How far is he from the pole at these moments? Take the speed of the sound to be 330m/s and ignore any sound reflection from the ground.

2007-10-17 00:50:15 · 1 answers · asked by Anonymous

A.T..I.N

2007-10-16 22:42:20 · 3 answers · asked by Anonymous

(a) How much work must one do (against gravity) to get a stone block (m=4000 KG) from the base of the pyramids to its place 30 m above that?

(b) How much Force (F) would a crane need to apply to lift the block into place (at a constant speed, so acceleration is very small)?

please show steps!!

2007-10-16 22:38:19 · 5 answers · asked by Anonymous

why dont the coffee beans just get pushed out of the way when the blade just begins to push on them?

Please explain

2007-10-16 22:25:26 · 4 answers · asked by Anonymous

I understand that the formula is:

velocity = frequency x wavelength

But why does 69.9 cm become 0.699? Why do we divide it by 100?

2007-10-16 19:48:53 · 2 answers · asked by lovemeplease 2