Physics - March 2007

2007-03-07 06:08:52 · 7 answers · asked by Anonymous

A helicopter lifts a 69 kg astronaut 11 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/10.
a) How much work is done on the astronaut by the force from the helicopter?
(b) How much work is done on the astronaut by her weight?

2007-03-07 05:43:26 · 2 answers · asked by Rogue Bagel 2

A block lies on a horizontal frictionless surface and is attached to the free end of the spring, with a spring constant of 50 N/m. Initially, the spring is at its relaxed length and the block is stationary at position x = 0. Then an applied force with a constant magnitude of 2.8 N pulls the block in the positive direction of the x axis, stretching the spring until the block stops.
Assume that the stopping point is reached.

What is the blocks position when its kinetic energy is maximum?


Value of Kinetic energy = ?mJ

2007-03-07 05:25:54 · 2 answers · asked by Rogue Bagel 2

has an output of 32.0 A at 120 VAC. Find the input voltage and current, assuming 95% effiecientcy

2007-03-07 05:24:59 · 2 answers · asked by spotted_dog87 2

to the system when a current of unknown magnitude is sent through both wires. The wires are 26.5 cm long and have a center-to-center seperation of 0.0525 cm. Find the current.

2007-03-07 05:19:19 · 1 answers · asked by spotted_dog87 2

2007-03-07 05:19:14 · 6 answers · asked by wencar29 1

the Space shuttle lost a satellite which was being towed by a long conducting cable through the Earth's magnetic field. The cable was 12.2 miles in length, and the shuttle was moving at 18,500 miles per hour. Assume that the cable was moving perpendicular to the Earth's magnetic field of 5.50 x 10^(-5) T, and calculate the voltage generated.

2007-03-07 05:17:15 · 1 answers · asked by spotted_dog87 2

What if we could convert a human body energy to light energy, could we achieve lightspeed if we were light? Is this even a possiblility in the far future? Kinda like Star Trek and their "beaming" technology..

2007-03-07 05:00:31 · 7 answers · asked by riogrande_texas 1

I seem to remember hearing a story of a famous physicist who around the turn of the century (last) claimed all the questions of physics had been answered except for one small issue of whether light is a wave or a particle. Does anyone remember the details of this story?

2007-03-07 04:49:22 · 1 answers · asked by Alex Tsakiris 1

Does negative time mean negative space? Would traveling backwards in time propel one from a body instead of towards it?

2007-03-07 04:45:24 · 5 answers · asked by Luis 6

It can't be created... so no "Big Bang" theories please.. that was energy already,, where did that energy come from. If it can't be created then there isn't any energy right? or what? I'm confused.

2007-03-07 04:43:33 · 5 answers · asked by riogrande_texas 1

2007-03-07 04:43:17 · 10 answers · asked by gerard2856 1

The crow flies with under a lamppost at half its height
with constant speed v.

2007-03-07 04:41:25 · 1 answers · asked by Alexander 6

Question: A 2700 ohm resistor and a 1.1 x 10^-6 F capacitor are connected in a series across a generator (60.0 Hz, 120 V). Determine the power delivered to the circuit.

My Approach: I found the reactance capacitance and got 2409 ohms. Then I plugged numbers into V = IZ to get current. Notably, I divided 120 V by square root of 2 (for peak value purposes). My answer for current was I = 2.35 x 10^-2 A. Then, I plugged the current in the P = IV cos (0) and got P = 2.8 W. Are my numbers correct? My main question comes when I divided voltage by square root of 2. Appreciate all the help I can get!

2007-03-07 04:41:12 · 2 answers · asked by Jimmy 3

can two small electric motors connected to each other so that one acts acts like a generator to the other. if you connect their shafts to each other and their wires and if you spin the motors will they keep spining off their own power.

2007-03-07 04:35:52 · 6 answers · asked by slojojames2 1

So there's matter and antimatter, black and white, light and dark. The universe seems full of opposites. However is there such a thing as negative gravity? Is gravity the only constant force in the universe?

2007-03-07 04:31:05 · 4 answers · asked by Luis 6

an artificial satellite is moving in a circular orbit with spd equal to half the escape velocity from earth's surface.If the satellite is stopped suddenly and is allowed to fall freely onto the earth,what is the speed with which it strikes the surface of the earth

2007-03-07 04:30:21 · 1 answers · asked by Anonymous

In movies they show people staying stationary on earth, but the earth and sun are moving, so wouldn't time travel in either direction remove the tether of gravity because you'd have to stay stationary?

2007-03-07 04:28:21 · 6 answers · asked by Luis 6

This is not homework. But I have found both men credited for the formula or law. Many Thanks.

2007-03-07 04:25:02 · 4 answers · asked by Dovey 7

I have 5 volts battery at the bottom and three resistors - 2 in series parallel to the battery (1 and 2 ohms) and one above them parallel to them (3 ohms). Please help me to calculate voltage drop accross each one.
How to I calculate current through those two lines - I know the total current and I know that the sum of those two is total. Helppppp!

2007-03-07 04:20:08 · 4 answers · asked by m666777 1

what are 3 ways to increase the resistance of copper wire

what are 3 ways to increase the current flowing through the copper wire

2007-03-07 04:03:29 · 5 answers · asked by BoSox 007 3

a series circuit has a total resistance of 50 ohms and an applied potential difference of 4 volts. the amount of charge passing any point in the circuit in 5 seconds is...

2007-03-07 04:02:11 · 2 answers · asked by BoSox 007 3

ahuhuhuhuhuhu... tomorrow I need to finish our project tomorrow waaa... its all about making a concept of a parking lot system meaning that i must make the concept of the whole system including switches, elevators, traffic lights etc... My god I am just 3rd yr COE but still i did'nt learned that much coz the instructors didn't thought us that us that much... ahuhuuhu... I just got finished with thet traffic lights system with swiches... but damn.. the concept of an elevator is damn hard to understand... 1st I had a 12v DC motor damn.... i know how to set it on its position for lifting... but theirs problems i encountered

1st is that how could a manupulated the up n downs of the elevator
by switching its poles with only one switch..

2nd when the elevator reaches the top or down how could it switch
its power to off..

3rd and finally after being off at the top how could i lock it with out letting if fall from the top.

Help me please i'm almost crazy of thinking.. thanks a lot T_T

2007-03-07 03:54:48 · 5 answers · asked by Chris 2

2007-03-07 03:49:30 · 4 answers · asked by thirteen 1

2007-03-07 03:31:31 · 4 answers · asked by fourjayjames 1

answer should be supported with principles of physics

2007-03-07 03:08:54 · 2 answers · asked by Saagar M 1

During a 56 ms interval, a change in the current in a primary coil occurs. This change leads to the appearance of a 6.0 mA current in a nearby secondary coil. The secondary coil is part of a circuit in which the resistance is 12 . The mutual inductance between the two coils is 4.1 mH. What is the magnitude of the change in the primary current?

2007-03-07 03:06:47 · 2 answers · asked by layc_510 2

A cart of mass 380 grams is temporarily held stationary on an incline at 3.7 degrees to horizontal.
•A mass of 75.00001 grams is attached to the cart by a string over a pulley located at the bottom of the incline; the mass hangs freely from the string.
•When the cart is released, what will be its acceleration in the direction down the incline?
•Sketch and label a reasonable facsimile of a scaled diagram showing the forces acting on the cart.

2007-03-07 02:47:26 · 2 answers · asked by tanie 1

Coasting from rest down a certain hill, whose slope is variable, I reach a speed of 13.89 m/s at the bottom. If I coast from rest down the first half of the hill I reach a speed of 12 m/s. Ignoring the effects of air resistance and friction:
•How fast would I therefore be going if I coasted from rest down the second half of the hill?
•How high would I have to climb from the bottom of the hill to reach the halfway point?

2007-03-07 02:46:38 · 1 answers · asked by tanie 1

At what velocity would a satellite orbit a planet of mass 20 * 10^24 kg at a distance of 39700 km from the center of the planet?
•What would be the orbital KE of the satellite if its mass was 790 kg?
•How much would PE and KE of this satellite change as the satellite moved from a circular orbit of radius 39700 km to a circular orbit of radius 43670 km?

2007-03-07 02:45:40 · 1 answers · asked by tan 1