Physics - October 2007

the emf produced by an ac genrator is given by e=wNBA sin wt. In the SI system what is the value of w for a frequency of 60 Hz?

a) 60 Hz
b) 120 rad/s
c) 2 pi rad/s
d) 377 rad/s
e) 577 Hz

please help and explain this to me guys!! thanks!!

2007-10-12 14:12:13 · 2 answers · asked by Anonymous

A skater moving at 5m/s begins to decelerate at 2m/s each second. How fast will it be moving after 4 seconds.
show me how you did it. tnx

2007-10-12 13:56:02 · 2 answers · asked by Anonymous

I would like to know weather it is inward,outward or not at all

2007-10-12 13:53:32 · 3 answers · asked by jiji v 1

My teacher asked a question asking which of the following are always true, and one of the statements was:

A constant force is needed to keep the object moving at a constant velocity.

I know that maybe he said it's false because it should be acceleration instead of velocity, but I think that it may be true; at least up to what we have covered so far.

If something is moving in a circle it takes a constant force towards the center of the object to keep it at a constant velocity, and if something is moving in a straight line it takes a constant force of 0, to keep it's velocity constant.

Did I miss something or am I mistaken?

2007-10-12 12:56:22 · 2 answers · asked by greeneggs4spam 3

2007-10-12 12:54:56 · 1 answers · asked by brozippo 2

A 1.4 kg block is released from rest and allowed to slide down a frictionless surface and into a spring. The far end of the spring is attached to a wall, as shown. The initial height of the block is 0.38 m above the lowest part of the slide and the spring constant is 432 N/m.

(a) What is the block's speed when it is at a height of 0.25 m above the base of the slide?
___m/s
(b) How far is the spring compressed?
___ m
(c) The spring sends the block back to the left. How high does the block rise?
__m

2007-10-12 12:52:48 · 1 answers · asked by Anonymous

and that the movie and series called "stargate sg-1" is the result and not the preamble of time-space travel. Now that you know this, I am gone. You did not see me. Follow the white rabbit,...if you dare. I told you Id tell them.51515151515151515151515151515151515151515151515151515and dna . A=A. Coroniun Oritholelliun. What is ...is.

2007-10-12 11:43:22 · 4 answers · asked by alatheaescapedez 1

A person pushes a 13.0 kg lawn mower at constant speed with a force of 78.0 N directed along the handle, which is at an angle of = 45.0° to the horizontal.

1. Calculate the horizontal retarding force on the mower

2. Calculate the normal force exerted vertically upward on the mower by the ground.

3. Calculate the force the person must exert on the lawn mower to accelerate it from rest to 1.2 m/s in 2.0 seconds

2007-10-12 11:24:58 · 2 answers · asked by angeleyez000000 2

using your age, weight, etc. thanks :]

2007-10-12 11:18:59 · 2 answers · asked by ms.problemsolver 3

If two snowboarders on top of a mountain let gravity pull them to the bottom of the slope, who would reach the bottom first if snowboarder #1 weighs 70 pounds more than snowboarder #2 and there was no wind or ground resistance?

Additional info (if needed): Slope of the mountain has a 30 degree decline.

2007-10-12 11:00:25 · 4 answers · asked by Odrama 1

I understand that longitudinal waves are some kind of electromagnetic phenomenon, but I don;t understand how they may be distinct from commonly referred to electromagnetic forces.

2007-10-12 10:59:42 · 1 answers · asked by blue weaver 1

An elevator of mass m rises a vertical distance h with upward acceleration equal to one-tenth g. how much work does the elevator cable do on the elevator

I know the answer is 1.1 mgh but i dont know how to get this . when i do it i get .1mgh so i dont know where the extra 1 comes in

2007-10-12 10:58:44 · 1 answers · asked by fhsdjfsd 2

http://s223.photobucket.com/albums/dd78/floodtl/?action=view¤t=AppleBattery.jpg

2007-10-12 10:36:56 · 3 answers · asked by Anonymous

in kJ

2007-10-12 10:19:37 · 2 answers · asked by scoota 1

also, find the orbital velocity of a satellite at this altitude.

2007-10-12 09:56:16 · 2 answers · asked by Anonymous

I'm trying to figure out these problems:

A model rocket carries no fuel; it is set in motion entirely by its ground-level launcher. 8.2 s after being launched, the rocket lands on the ground 415 m from the launcher.
(a) Find a component description of the rocket's initial velocity. v0x = ___m/s
v0y =____ m/s

(b) Find the speed and directional angle at which the rocket was launched. speed___ m/s
angle____ °

(c) If the launch occurs at t = 0, at what two instants t does the rocket have a speed of 47 m/s? first time ____s
second time ____s

for the first two, I tried using this formula: d=v0t + 1/2at^2. I filled everything in and got 415=v0*8.2 +1/2 * 9.8 * 8.2^2 (Im using * as multiplication signs)

I got 10.4 m/s, but the computer says I'm wrong, what am I doing wrong, and how do I do the other problems?

thanks.

2007-10-12 09:55:34 · 2 answers · asked by nfcu016 3

2007-10-12 09:41:52 · 5 answers · asked by Anonymous

Electromagnetic radiation at the blue end of the visible spectrum has a wavelength of 400 nm. Calculate the frequency of the radiation.

2007-10-12 09:26:16 · 3 answers · asked by Darly F 1

What happens when the temperature reaches the absolute zero?

2007-10-12 09:20:42 · 5 answers · asked by f4u2nv69 2

A dockworker applies a constant horizontal force of 77.0N to a block of ice on a smooth horizontal floor. The frictional force is negligible. The block starts from rest and moves a distance 11.0m in a time 5.30s .

2007-10-12 09:11:54 · 2 answers · asked by elturi2k@sbcglobal.net 1

A particle travels between two parallel vertical walls separated by 11m. It moves toward the opposing wall at a constant rate of 6.3m/s. It hits the wall at the same height and the acceleration of gravity is 9.8m/s^2. How would I be able to find the speed of the particle when it hits the opposing wall and then how can I find at what angle with the wall will the particle strike?

2007-10-12 08:33:57 · 2 answers · asked by kira 2

2007-10-12 08:19:36 · 3 answers · asked by marcus b 1

it was introduced by franz anton mesmer

2007-10-12 08:15:38 · 2 answers · asked by Anonymous

Someone was telling me that you can actually see IR lights with your eyes if you are in a dark enough place (with the naked eye). Is this true? If so, can you back up the facts?

2007-10-12 08:06:17 · 8 answers · asked by jorge d 1

Okay so there are two blocks (m1 = 1kg & m2 = .5kg), lying together on a frictionless surface. A constant force of .10N is applied to block m1, pushing both blocks across the table to the right 3.33m in 10 seconds. Then a force of -.10N pushes on block m2, pushing both blocks to the left -3.33 meters in 10 seconds.
What is the acceleration magnitude of the 2 blocks?
In the first scenario, 2 horizontal forces act on m1: the external force and the contact force (P21) acting to the left. Newton's law gives: F - P21 = m1a. The applied force must make both blocks accelerate. Solve the expression for the contact force acting on m1:
N
On block m2, only the contact force (P12) from m1 is acting on it. Thus P12 = m2a. Solve this for the contact force acting on m2: N.
Now reverse the scenario, with the force acting from the left. Solve for the contact force P12, and the contact force acting on m1.

Thanks for the help!

2007-10-12 07:56:28 · 1 answers · asked by Bill 1

I am picturing *one location on the x-axis, *one location on y-axis, and *one location on the z-axis. I visuallize these plotting one single point in three-dimensional space, similar to a standar x-y graph. How is this *point supposed to represent a vector????? Does the vector start from the origin and go through this point?

2007-10-12 07:48:25 · 7 answers · asked by RogerDodger 1

I know that the mass shot from the cannon is 0.787 kg and the end of the cannon's barrel is at 6.9m and the initial velocity vi of the projectile has a horizontal component of 4.6m/s. The projectile rises to a height of delta y and strikes the ground at a horizontal distance delta x past the end of the cannon's barrel, and the acceleration of gravity is 9.8m/s^2. I have to find out the time it takes for the projectile to reach its maximum height, so if anyone could explain what I could do or if there are equations I could use to find the maximum height that would be helpful and appreciated.

2007-10-12 07:42:45 · 3 answers · asked by <3DA<3 1

2007-10-12 06:52:59 · 4 answers · asked by Anonymous

2007-10-12 06:45:22 · 5 answers · asked by Romazejha D 1

After a skiing accident, your leg is in a cast and supported in a traction device, as shown in Figure 6-27. Find the magnitude of the force F exerted by the leg on the small pulley. (By Newton's third law, the small pulley exerts an equal and opposite force on the leg.) Let the mass m be 3.30 kg, and the angle be 29.0°.

Figure:
http://i190.photobucket.com/albums/z204/inthisdarcness/06-22alt.gif

Please help if you can. I have worked at it, but I get the wrong answer everytime.

2007-10-12 06:33:35 · 2 answers · asked by Imagine 1