Physics - March 2007

A convex mirror has a focal length of 20 cm. Determine the object location for which the image will be one half as tall as the object.

2007-03-11 14:26:43 · 1 answers · asked by Kitana 2

I need to know if the temperature would add up to create and environment in which Freon would decompose into phosgene gas. (Yes, I know freon is illegal. I am asking this for a report)

2007-03-11 14:15:27 · 3 answers · asked by starwindxero 1

The Concorde flies at Mach 1.3. What is the angle between the direction of propagation of the shock wave and the direction of the plane's velocity?

2007-03-11 14:00:29 · 1 answers · asked by kbeauty 4

a roller coaster of mass 396 kg starts stationary at pointA, where H1=37.9 m and a while later is at point B, where H2 is 9 m. the acceleration of gravity is 9.8 m/s^2. what is the potential energy of the cart relative to the ground at A ? and what is the speed of the cart at B, ignoring the effect of friction ?

2007-03-11 13:36:53 · 1 answers · asked by Anonymous

The electric field everywhere on the surface of a thin spherical shell of radius 0.750 m is measured to be equal to 890 N/C and points radially toward the center of the sphere. What is the net charge with the sphere's surface?

2007-03-11 13:21:47 · 1 answers · asked by Belle 3

a rigid assembly of a thin hoop (of mass m and radius R = 0.200 m) and a thin radial rod (of mass m and length L = 2.50 R). The assembly is upright, but if we give it a slight nudge, it will rotate around a horizontal axis in the plane of the rod and hoop, through the lower end of the rod. Assuming that the energy given to the assembly in such a nudge is negligible, what would be the assembly's angular speed about the rotation axis when it passes through the upside-down (inverted) orientation?

im kinda stuck.

2007-03-11 13:21:34 · 1 answers · asked by sergio SoIcy Martinez 2

i was out of town for few days and i didnt have time because i was in the hospital and i have more than 19 papers 2 do

question are

6)When snow on the ground melts, it (decreases or increases) atmospheric temperature.

7)the percentage of solar radiation reflected by an ocean is (less than,greater than) the percent reflected by a desert.

8)as the height above Earth's surface increases, the amount of gas in the atmosphere
a.increase b.decreases c.remains the same d.none of these

9) which of the following are not winds
a westerlies b.jet streams c.subpolar lows d.trade winds

10 A maritime air mass is likely to be
a.moist b.dry c. cold d.hot

11.weather front are
a. the beggining of a violent storm
b.the interraction of air masses
c.air masses with high or low temperatures
d.stationary air masses

2007-03-11 13:20:19 · 1 answers · asked by Tha best!! 2

a 100W light bulb is 20% efficient. That means 20% of the electric energy is converted to light energy.

a. how many joules does the light bulb convert into light each min it is in operation?

b. how many joules of thermal energy does the light bulb produce each min?

2007-03-11 12:55:47 · 2 answers · asked by Anonymous

2007-03-11 12:52:46 · 1 answers · asked by honeymopsy 1

a 15 Ohm electric heater operates on a 120V outlet.

a. what is the current through the heater?
b. how much energy is used by the heater in 30 sec?
c. how much thermal energy is liverated by the heater in this time?

be the first one to answer all the question gets a best answer sticker!!!

2007-03-11 12:51:21 · 1 answers · asked by Anonymous

2007-03-11 12:50:09 · 4 answers · asked by saad1224 1

A spaceship negotiates a circular turn of radius 2885 km at a speed of 31000 km/h.
(a) What is the magnitude of the angular velocity?
in rad/s
(b) What is the magnitude of the radial acceleration?
in m/s2
(c) What is the magnitude of the tangential acceleration?
in m/s2

i'm stumped with this hw problem, i know that C)=0, but im clueless on A and B.

2007-03-11 12:33:57 · 1 answers · asked by sergio SoIcy Martinez 2

Hint: All Atomic-clocks are based on the answer to my question.

2007-03-11 12:13:52 · 1 answers · asked by Ke Xu Long 4

What fraction of the power radiated by the sun is intercepted by the planet Mercury? The radius of Mercury is 2.44 x 10^6 m, and its distance from the sun at the moment is 5.79 x 10^10 m. Assume that the sun radiates uniformly in all directions.

2007-03-11 11:59:20 · 2 answers · asked by nemlo23 2

What pressure does a 150 pound woman exert on the floor when she balances herself on just one of her heels? Note that her heels have an average radius of 0.8 inches.

2007-03-11 11:35:35 · 3 answers · asked by help_with_physics 1

Two trains on separate tracks move toward one another. Train 1 has a speed of 140 km/h and train 2 a speed of 65.0 km/h. Train 2 blows its horn, emitting a frequency of 500 Hz. What is the frequency heard by the engineer on train 1?

i have the equation F'=F(velocity of sound +/- speed of receiver/speed of sound +/- speed of source of sound) but im sitll not getting the right answer....

2007-03-11 11:22:52 · 4 answers · asked by kbeauty 4

Vulcan science officer used the calculation of Pi to crash the computer

2007-03-11 11:12:56 · 2 answers · asked by Steve Z 1

If I drive at a steady 40 miles per hour, and the car in front drives at a steady 45 miles per hour, the gap between us will steadily increase. Now an increase in speed is acceleration, but how do I describe the increasing gap between two vehicles which aren't accelerating?

2007-03-11 11:11:53 · 13 answers · asked by Not Just Another Sheep 2

2007-03-11 11:00:34 · 6 answers · asked by Fuarosa P 1

A car with a mass of 1200 kg moves at 18 m/s. What braking force is needed to bring the car to a halt in 10 s?

2007-03-11 10:53:27 · 2 answers · asked by Dirck G 1

2007-03-11 10:46:56 · 3 answers · asked by saqib 1

2007-03-11 10:46:28 · 4 answers · asked by saqib 1

2007-03-11 10:45:07 · 3 answers · asked by saqib 1

I have heard centrifugal force described as the natural force that pushes an object swung in a circle away from the center.

I have also read a book, written by a Physics teacher, that says centrifugal force is a myth.

I would like some extra opinions, please. If you could cite a source, that'd be great.

2007-03-11 10:34:05 · 2 answers · asked by PHI 1.618 2

A system has 1525 particles of protons and electrons, and a net charge of -5.456*10^-17.
How many electrons are there and what is the mass of these electrons?
How do I do this?

2007-03-11 10:18:52 · 2 answers · asked by veghead566 1

1.) The feet of a standing person of mass m exert a force equal to mg on the floor; and the floor exerts an equal and opposite force upwards on the feet, which we call the normal force. During the extension phase of a vertical jump, the feet exert a force on the floor that is greater than mg, so the normal force is greater than mg. We can use this result and Newton's second law to calculate the acceleration of the jumper: a=Fnet/m=(n-mg)/m. Using energy ideas, we know that work is performed on the jumper to give him or her kinetic energy. But the normal force can't perform any work here, because the feet don't undergo any displacement. How is energy transferred to the jumper?

2.) In most circumstances, the normal force acting on an object and the force of static friction do no work on the object. However, the reason that the work is zero is different for the two cases. In each case, explain why the work done by the force is zero.

Can I please get detailed responses for these? Thanks!

2007-03-11 10:18:33 · 1 answers · asked by Lakers 1

Please help me!

2007-03-11 10:15:40 · 6 answers · asked by silver 2

height, of a regular 1 pint beer glass??

Check this out when u next get to the pub! You'll be relatively surprised!

2007-03-11 10:12:21 · 5 answers · asked by el_barto_ash 1

the rest of the question is, find thew speed and direction of the 2 objects just after the collision.

2007-03-11 10:04:14 · 4 answers · asked by kimberly b 1

2007-03-11 09:55:38 · 14 answers · asked by Anonymous