Physics - October 2007

2007-10-13 19:42:47 · 9 answers · asked by Anonymous

equal its potential energy?

at all points of the fall
halfway to the floor
just the instant before it hits the floor

2007-10-13 19:41:30 · 1 answers · asked by Too CooL 3

High-speed elevator is being planned to lift a total load of 4000kg at 6.0m/s. the winding drum is to be 1.8m in diameter. (a) Neglecting losses, how much power is required from the driving motor? (b) At what angular speed should the power be developed?

2007-10-13 19:32:49 · 1 answers · asked by Anonymous

A 1.0 hp motor rotates at 1200 rpm. How much torque can it exert?

2007-10-13 19:27:28 · 2 answers · asked by Anonymous

If it can't slow down, what happens to it. If I shine a torch between two mirrors why does it disapear when the light is switched off. I have tried to imagine a photon like a bullet but with endless velosity but I know that it can't work, I am only capable of thinking in practicable terms, so forgive me if it is a stupid question

2007-10-13 19:21:06 · 4 answers · asked by Anonymous

2007-10-13 18:57:04 · 4 answers · asked by xerxes l 1

The torque used to tighten a 1/4 inch. bolt should not exceed 80 lb. inch. Express this torque in Newton-meters.

2007-10-13 18:46:25 · 1 answers · asked by Anonymous

a rotating platform is to be used to test aircraft equipment under acceleration of 6g. If the acceleration is 50 cm from the axis, What angular speed is needed?

2007-10-13 17:08:15 · 2 answers · asked by vino 1

A car is travelling East at a horizontal speed of 56.3km/h and rain is falling vertically with respect to Earth. The traces of rain on the side windows of the car make an angle of 65 degrees with the vertical. How would I find the magnitude and the velocity of the rain with respect to the car.

2007-10-13 16:48:58 · 2 answers · asked by KE 1

(I hate to repost this, as I'm sure there is some rule against it, and for that I do apologize. I'm only doing it because I don't have a great deal of time left to complete the assignment, and I didn't receive a great deal of answers last time (but the answers were excellent may I add, so thank you!!!))

I'm writing this report on the physics behind computers throughout history, and I'm not quite sure what to put next... So far I've written about:

~ Thermionic Emission - Used in the old-fashioned vacuum tubes by using heat to emit electrons.
~ Transistors - Basically put what they are and how they work.
~ Magnetic Core Memory - Explaining how information is stored in the hard drive of the computer.

Any more ideas would be excellent!

2007-10-13 13:38:32 · 6 answers · asked by Sean 3

A long straight wire is carrying a current of 2.4 A in a region where the magnetic field is perpendicular to the wire. If the magnetic field is 0.52 mT, what is the magnitude of the force on 3.0 m of the wire??

a) 1.2 * 10^-3 N
b) 3.7 * 10^-3 N
c) 7.2 * 10^-3 N
d) 3.7 N
E) 7.2 N

please help and explain thanks

2007-10-13 13:06:47 · 1 answers · asked by Anonymous

an electron is moving at 2.5 * 10^6 m/s perpendicular to a 3.5 mT magnetic field. What is the radius of its path?

a) 5.1 cm
b) 3.9 cm
c) 1.6 cm
d) 4.1 cm
e) 2.0 cm

please help and explain thanks

2007-10-13 13:01:11 · 2 answers · asked by Anonymous

A periodic sinuous track is installed on an uniform plane slope, such that it intersects the straight fall line at regular intervals. A boxcar with wheels rolls without friction down this track, so that if left to itself it will gain speed as it descends due to gravity alone. Is it possible to build a mechanical apparatus wholly inside the boxcar, containing its own energy source, that will counteract this freefall, so that the boxcar can maintain speeds not exceeding some maximum? No use of jets or propellers or magnets interacting with the world outside the boxcar is allowed, this is a purely Newtonian problem, the apparatus must be totally enclosed inside the boxcar. Assume that the wheel design guarantees that the boxcar will never derail, like a roller coaster car. Also assume that the boxcar is able to dissipate heat energy from its descent, which is necessary in order to maintain average speed.

2007-10-13 11:52:18 · 4 answers · asked by Scythian1950 7

An object at rest has three forces acting on it. The first force is 129 N acting along the positive x-axis. The second force is 159 N acting at an angle of 20 degrees relative to the positive x-axis.

2007-10-13 11:24:39 · 1 answers · asked by Anonymous

A particle moves horizontally in uniform circular motion, over a
horizontal xy plane. At one instant, it moves through the point at coordinates (4.00 m,
4.00 m) with a velocity of iˆ 00 . 5 − m/s and an acceleration of jˆ +12.5 m/s2. What are the
(a) x and (b) y coordinates of the centre of the circular path?

2007-10-13 11:01:17 · 2 answers · asked by pat l 2

What should be the spring constant k of a spring designed to bring a 1200 kg car to rest from a speed of 95 km/h so that the occupants undergo a maximum acceleration of 5.0 g?
=.........N/m

2007-10-13 10:47:44 · 1 answers · asked by Nikita 1

This problem has confused me for awhile now.

A baseball is thrown at an angle of 25 degrees relative to the ground at a speed of 23.0 m/s. If the ball was caught 42.0 m from the thrower, how long was it in the air? How high was the tallest spot in the ball's path?

2007-10-13 10:36:14 · 2 answers · asked by redalert 2

How much the extra work is required to stretch it an additional 11.5 cm? Answer in units of J.

2007-10-13 10:35:35 · 2 answers · asked by mira s 1

2007-10-13 10:32:58 · 3 answers · asked by navya 1

I believe that time is an energy-related function that is asymptotic, that is, it has a limit that does not allow traveling backwards in time. "Time travel" can only occur when you accelerate such that time begins to occur more slowly for you than for everyone else, therefore you are in effect "traveling to the future." This is in agreement with relativity and with what others say. You can accelerate as much as possible, traveling farther into "the future," but NEVER into the past, and when you stop you reach (I wouldn't call it "transport" into) a time in the future relative to the time that elapsed for everyone else. Since you were absent from any period in between (you were "time traveling"), and you arrive at a future endpoint, no paradox can exist. There are NO two of you at any one time. You only exist where you are whenever you are: in the current time, "time traveling" faster relative to everyone else, or at the future endpoint after you finished your "time travel." Opinions?

2007-10-13 10:32:26 · 5 answers · asked by Liquidator1 3

A 85 kg trampoline artist jumps vertically upward from the top of a platform with a speed of 3.0 m/s. (Ignore small changes in gravitational potential energy.)

(a) How fast is he going as he lands on the trampoline, 3.0 m below?
= 8.234 m/s

(b) If the trampoline behaves like a spring with spring stiffness constant 5.2 104 N/m, how far does he depress it?
=.........m

- Please help me how to do part b, i already got part a, which is right, but i don't get how to find part b, so please if you could help me, i would really appreciate it, Thanks :)))))

2007-10-13 10:32:24 · 5 answers · asked by Nikita 1

What is the kinetic energy of the ball at the highest point of its motion? Answer in units of J.

2007-10-13 10:31:59 · 1 answers · asked by mira s 1

A ball of mass .150 kg is dropped from rest at a height of 1.25m. It rebounds from the floor to reacha height of .960 m. What impulse was given to the ball by the floor?

2007-10-13 10:31:39 · 1 answers · asked by Ashley P 1

i have to do a report on how newton's laws apply with gravity and i have a good idea but i dont have enough to write a repot on it... Any Help?

2007-10-13 10:27:59 · 2 answers · asked by Anonymous

According to Wikipedia's "red shift" article, the red shift of distant galaxies is a combination of Dopple shift, special relativity, and the stretching of each photon during the time it takes to reach the observer. If the latter is correct, it means that energy is not conserved.

I think the writer is confused about the type of coordinate system be used. Is it an expanding coordinate system, or is the distance between grid lines constant in terms of meters?

I believe the length of a laser pulse will increase over billions of years; a one nanosecond pulse will start 300 millimeters long, and after a few billion yeats, it will be twice as long. But I doubt if the individual photons will be lengthened.

Any brainiacs care to comment?

2007-10-13 08:38:12 · 2 answers · asked by Anonymous

A 90 kg fullback runs east with 4.9 m/s. He is tackled by 94 kg opponent running north with 3 m/s. The collision is perfectly inelastic.
Find the speed and dircetion of the players after tackle.

After an elastic collision, how do you find the energy lost(like mechanical energy)?

2007-10-13 07:42:22 · 1 answers · asked by ひいらぎ 5

Life civilisations have lived on Mars. Why doesn't our Governments admit that we are not alone. Mars mathematical constructions and archetectialals teams have been working on this for 30 years viewed by NASA, CIA, MI5,6, FBI, Interpol and the UK Government, USA Government, Australian Govnt, Italian, France,Germany. Not including new east european states or russian lands

2007-10-13 07:32:07 · 4 answers · asked by Anonymous

The handle of the lawn mower makes an angle of 22 degree with the horizontal. If the boy pushes with a force of 135N, what are the horizontal and vertical components of the force?

2007-10-13 07:00:26 · 1 answers · asked by ? 2

????

2007-10-13 06:36:52 · 2 answers · asked by Anonymous

PLEASE HELP i would appreciate this so much if you help me on this about charged objects and neutral objects?
PROBLEM: how do charged objects interact with each other?

how did identical charged objects interact with each other? For example, how did one charged comb interact with the second charged comb?
PLEASE HELP I WOULD SO APPRACTIATE IT
like :
plastic comb (charged object in hand)
plastic comb(Charged object on watchglass)

How did differently charged objects interact with one another?
Conclusion:
how do neutral objects interact with charged objects?

how do charged objects interact with other charged objects?

How is this information useful in society?

2007-10-13 06:36:21 · 2 answers · asked by Anonymous