Physics - June 2007

Why is kinetic energy constant in circular motion even though i know speed is constant but there are top and bottom in a circle. Shouldn't the potential energy be converted to kinetic energy when the object moves from the top of a circle to the bottom?

For example,

.(top of circle)
| radius
|
.(center of circle)
|
| radius
.(bottom of circle)

Why is potential enrgy not converted to kinetic energy?

2007-06-05 04:57:32 · 5 answers · asked by Anonymous

How do I find the minimum and maximum base current to turn on, and then saturate a transistor

2007-06-05 04:53:57 · 4 answers · asked by SPARKFISH 4

A ball is projected horizontally from the top of a building. one second later, another ball is projected horizontally from the same point with the same velocity.

At what point inmotion will the balls be closest to each other?

will the first ball always be traveling faster that the second?

What will be the time difference between them when the ball hits the ground?

Can the horizontal projection velocity of the second ball be changed so that the balls arrive at the ground at the same time?

2007-06-05 04:36:33 · 4 answers · asked by Anonymous

A 500g model rocket is resting horizontally at the top edge of a 40m high wall when it is accidentally bumped. The bump pushes it off the edge with a horizontal speed of 0.5m/s and at the same time causes the engine to ignite. When the engine fires, it exerts a constant 20N horizontal thrust away from the wall.

a) How far from the base of the wall does the rocket land?
b) Describe the trajectory of the rocket while it travels to the ground.

2007-06-05 04:34:52 · 1 answers · asked by Subaki 1

If not, how do they know it will stop all atomic activity in a clump of matter?

2007-06-05 04:01:53 · 5 answers · asked by sassychickensuckerboy 4

I own a large swimming pool. It is 20FT wide, 40FT long, and has an average depth of 5FT. The top 2FT of pool is frozen solid (avg ice temp 24F, water temp avg below ice is 34F). Pool is enclosed so that outside conditions do not affect the pool environment. I rented a magic heater to run for 35 hours, dumping heat into the pool at a rate of 292,000 cal/sec. After 36 hours, is it safe to go swimming? what is the condition of the water at this time - e.g. half ice, half water, all water, some steam, what teamptures? Please show all your work.

Assumptions: 30.48 cm per foot
density of ice = 0.88 g/cc
density of water = 1 g/cc
specific heat of ice == 0.5 cal,g-c
specific heat of water = 1.0 cal/g-c
heat of fusion for water/ice = 80 cal/g
heat of vaporization water/steam = 540 cal/g

2007-06-05 03:58:00 · 3 answers · asked by fear_factor187 1

Yeah, do magnets lose their magnetism? And if so, how long?!

2007-06-05 03:40:15 · 4 answers · asked by Ton-ton 2

2007-06-05 03:29:25 · 2 answers · asked by nice_avril 1

Two dust particles each of mass 13 micro grams are floating on a gentle sream of air. What equal (positive) charge would each dust particle have to carry in order that their electrostatic repulsion should exactly balance their mutual gravitational attraction?

This has been driving me nuts... If there was a distance specified I'd have it in an instant. Can anyone help point me in the right direction?

2007-06-05 03:16:52 · 6 answers · asked by Anonymous

How would you describe the validity of Ohm’s law? What is meant by the statement that Ohm’s law is not a fundamental law of nature?

2007-06-05 03:13:58 · 5 answers · asked by walt 2

plz give me a detailed explanation in written .

thank you

2007-06-05 02:52:47 · 4 answers · asked by Anonymous

Here's what I know so far.

When measuring in radians, the angle measure is also the corresponding length of arc segment

(for Cos X = X)
Cos X = the length of the arc segment chopped by the angle theta

That means that the arc segment at .739 radians could be "unwound into a striaght line" and would be equal in length to the cos of .739 radians.

The cosine of .739 is the adjacent "leg" of the right triangle formed by the X axis, and the radius (as hypotenuse) from center of unit circle projected at .739 radians N of E until it hits the unit circle. Then dropping straight south.

Also I know that the sin of .739 radians is the absolute magniute of the upper endpoint of the arc segment from X axis.

I am very familiar with the visual understanding of trig and unit circle, including versine, exsecant, every trig function.

I still do not understand "why" the length of the unwound arc segment (into a striaght line) also equals the cosine for this radian angle measurement.

2007-06-05 02:45:54 · 6 answers · asked by Anonymous

2007-06-05 01:54:47 · 3 answers · asked by Anonymous

2007-06-05 01:50:47 · 1 answers · asked by Anonymous

2007-06-05 00:54:19 · 3 answers · asked by Kerri L B 1

2007-06-05 00:50:31 · 3 answers · asked by Kerri L B 1

2007-06-05 00:31:03 · 23 answers · asked by Kevin D 1

2007-06-04 22:46:01 · 6 answers · asked by Gaurav K 1

A sattelite is orbiting on an elliptical trajectory around the Earth, which is situated in one of the focuses. If the radius of the planet is R, the height of the satellite at apogee is h(max) and at perigee is h(min), what is the ratio between the minimum orbital velocity, v(min), and the maximum orbital velocity, v(max), of the satellite ?

2007-06-04 21:07:40 · 1 answers · asked by Anonymous

2007-06-04 20:42:42 · 7 answers · asked by Anonymous

Suppose there is a planet have a mass of Mp, orbiting a star with mass Ms.
When measured in the same time, the planet have the position vector of (Px i + Py j) and velocity vector of (Vx i + Vy j).
How can we calculate the the time needed for the planet to orbit the star, the orbit eccentricity and the aphelion and perihelion distance of the planet?

2007-06-04 19:44:30 · 3 answers · asked by seed of eternity 6

My question is based on the assumption (possibly a poor one) that if an object B moves away from an object A then that is the equivalent of object A moving away from object B (in the opposite direction of course).

If this assumption is correct then please help me with this thought experiment. Imagine there are two clocks A and B in space that are positioned next to each other. Lets say that clock B traveles away from clock A at a significant % of the speed of light and then returns back to A at that speed. Because of time dilation lets say that clock B measures only one minute has elapsed while clock A measures 1 hour. If my initial assumption was correct then it could equally be said that clock A traveled at a high speed away from clock B and therefore clock A should have the smaller elapsed time. My question is how can clock A register both 1 minute and 1 hour having elapsed?

Please point out the flaws in my argument because this problem has really been of interest to me

2007-06-04 19:42:01 · 11 answers · asked by corey s 1

2007-06-04 18:21:44 · 2 answers · asked by Anonymous

Suppose a person stands in 6 identical elevators under different circumstances. List from largest to smallest the 6 scale readings. Some may be equal. Answers should be in the form A >B =C>D

Conditions:
1) velocity up at 3m/s, acceleration up at 2m/s^2
2) velocity down at 3m/s, acceleration points up, but slows at
2m/s^2
3) velocity down at 3m/s, no acceleration (steady speed)
4) velocity up at 6m/s, acceleration speeding up at 2m/s^2
5) velocity down at 3m/s, acceleration speeding up at 2m/s^2
6) velocity down at 3m/s, falling at 9.8 m/s^2

Thankyou greatly!!!

2007-06-04 18:19:21 · 1 answers · asked by Subaki 1

A person walks first at a constant speed of 5.00 m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed over the entire trip? What is her average speed over the entire trip? How do I calculate this without knowing the distance traveled? I know that average speed equals the total distance over the total time...

2007-06-04 17:54:15 · 2 answers · asked by Anonymous

2007-06-04 17:43:18 · 8 answers · asked by sam m 1

like a regration

2007-06-04 16:16:53 · 5 answers · asked by Javier C 1

I need this question to be proven mathematically.
Thanx~!!

2007-06-04 15:38:27 · 3 answers · asked by MM 1

After a completely inelastic collision, two objects of the same mass and same initial speed are found to move away together at one third of the initial speed. Find the angle between the initial velocities of the objects.

2007-06-04 15:20:07 · 2 answers · asked by Anonymous

How do you convert them?

2007-06-04 15:05:16 · 4 answers · asked by Anonymous