Physics - March 2007

1) A thin rod length=1.5m is oriented vertically with its bottom end attached to the floor by means of a frictionless hinge. the mass of the rod may be ignored compared to the mass of an object fixed to the top of the rod. the rod starting from rest tips over and rotates downward. what is the angular speed of the rod just before it strikes the floor? what is the magnitude of the angular acceleration of the rod just before it hits the floor?

2)The front and rear sprockets on a bike have a radii of 9.00 and 5.10 cm. the angular speed of the front sprocket is 9.4 rad/s. what is the linear speed in cm/s of the chain as if moves between the sprockets and the centripetal acceleration in cm/s^2 of the chain as it passes around the rear sprocket?

please show your work and god bless!

2007-03-26 10:55:16 · 1 answers · asked by wade 2

2007-03-26 10:52:00 · 2 answers · asked by quetions1 1

What happens during radioactive decay?

2007-03-26 10:48:17 · 5 answers · asked by Linda M 1

I learned in science that lightning is static electricity but whenever i shock my self its blue but when theres lightning in the sky its yellow not blue

2007-03-26 10:48:00 · 2 answers · asked by Anonymous

What is the distance from the Earth's center to a point outside the Earth where the gravitational acceleration due to the Earth is 1/24 of its value at the Earth's surface?

Answer should be in meters.

2007-03-26 10:40:23 · 3 answers · asked by Jessie L 2

Describe some methods that would allow them to decrease their weight without decreasing their mass.

2007-03-26 10:39:38 · 2 answers · asked by Anonymous

A hypothetical planet has a radius 1.9 times that of Earth, but has the same mass. What is the acceleration due to gravity near its surface?

Answer in m/s^2 (downward).

2007-03-26 10:39:35 · 2 answers · asked by Jessie L 2

Calculate the acceleration due to gravity on Venus. The radius of Venus is about 6.06 x 10^6 m and its mass is 4.88 x 10^24 kg.

Answer should be in m/s^2.

And to those of you who have emailed me about not picking a best answer in a timely manner, I apologize but I must wait three hours before I do. I do not live on the computer and sometimes I am forgetful. If you would liked to be picked for best answer and I have forgotten to choose one in a timely manner, email me. I check email more frequently than yahoo. Thanks.

2007-03-26 10:38:24 · 2 answers · asked by Jessie L 2

A) Using Newton's Laws of Motion, explain what happens.

B) How does a headrest reduce whiplash?

2007-03-26 10:37:59 · 4 answers · asked by Anonymous

A woman whose mass is 54.7 kg stands at the rim of a horizontal turntable which has a moment of inertia of
338 kg m^2 about the axis of rotation and a radius of 2.26 m. The system is initially at rest and the turntable is free to rotate about a frictionless, vertical axle through its center. The woman then starts walking around the rim in a clockwise direction (viewed from above) at a constant speed of 0.873 m/s relative to the ground.

What will the motion of the turntable be, relative to the ground?
(pick best one)
1. at rest, non-rotating
2. rotating counterclockwise
3. rotating clockwise

What is its angular speed? Answer in units of rad/s.

How much work does the woman do to set the system into motion? Answer in units of J.

2007-03-26 10:37:24 · 1 answers · asked by emz 1

If you give it a hard push with your hand, it slides across the table then slowly comes to a stop. Use newton's first law of motion to answer the following:

A) Why does the book remain motionless before the force is applied?

B) Why does the book move when the hand pushes on it?

C) Why does the book eventually come to a stop?

D) Under what conditions would the book remain in motion at a constant speed?

2007-03-26 10:31:38 · 4 answers · asked by Anonymous

12) A stroboscope is a light that flashes on and off at a constant rate. It can be used to illuminate a rotating object, and if the flashing rate is adjusted properly the object cant be made to appear stationary. What is the shortest time between flashes of light that will make a 3 blade propeller appear stationary when it is rotating with an angular speed of 16.7 rev/s? and what is the next shortest time?

20)A person is riding a bicycle and its wheels have an angular velocity of +20.0 rad/s. then the brakes are applied and the bike is brought to a uniform stop. during braking the angular displacement of each wheel is +15.92 revolutions. how much time does it take for the bike to come to rest and what is the angular accelerations in rad/s^2 of each wheel?

please show all work that you can even if you can only help with one of the problems. thanks so much!

2007-03-26 10:12:52 · 2 answers · asked by poker22only 2

2007-03-26 09:43:40 · 4 answers · asked by Anonymous

Four bricks of length L, identical and uniform, are stacked on top of one another , in such a way that part of each extends beyond the one beneath.
The distance from the edge of the table to the edge of the bottom block is a1, from the edge of that block to the edge of the next block is a2, and so forth until a4 which is the distance from the edge of the top block to the edge of the one directly below it.
h is the distance from the farthes t edge to the table, namely a1+a2+a3+a4
L is smaller than h



Find, in terms of L, the maximum values of the following, such that the stack is in equilibrium.

a1=_______*L
a2=_______*L
a3=_______*L
a4=_______*L
h=________*L

2007-03-26 08:44:19 · 1 answers · asked by x2carlosp 2

What if you just put these mirrors as walls, so the whole room is just covered in mirrors. Then, you like put light in there or something. Won't it just keep going? So if you can somehow convert that power into a spaceship or something, can't that make infinite power? It will keep going forever, unless you turn off the source of power, or take out a mirror.

2007-03-26 08:44:09 · 6 answers · asked by Nick B. 3

could you seperate the dioxide from the hydrogen in water ( i am not a scientist so simple answers please)

if you can why do they not invent something for deep sea divers and people on submarines to use that converts the sea water so they have unlimited amounts of oxygen without re survacing

i thought about this in the middle of the night and i havent stopped thinking about it since

the reason i asked what hydrogen is used for is because it was seperated from the water then i take it it would be a wasted by product wouldnt it

thank you for your answers

xxx

2007-03-26 08:15:23 · 7 answers · asked by vici 4

Hi. say I have two systems

i(t) --> [sys1] --> u(t) --> [sys2]--> o(t)

Where a pulse signal is generated i(t) and goes through the systems. But by the time it reaches u(t) and o(t) it is no longer a (delta) impulse pulse but a wider pulse.

I am then told that the signal I would have gotten at o(t) if u(t) was a delta pulse can be obtained by deconvolving o(t) with u(t). Please can you explain why this is?

2007-03-26 08:14:34 · 1 answers · asked by Appel 2

A. when the new model better explains the observatrions.
B.old models should never be replaced.
C. When the new model is better excpted by the public
D. When a scientist proves that the new model is correct.

2007-03-26 08:12:07 · 3 answers · asked by ladona c 1

spark chamber is a topic in modern physics

2007-03-26 08:11:30 · 1 answers · asked by fly 1

What kind of energy conversion is occurring when a candle burns?
A nuclear energy to electromagnetic energy and heat energy
B chemical potential energy to heat energy and nuclear energy
C chemical potential energy to heat energy and electromagnetic energy
D mechanical energy to electromagnetic energy and heat energy

2007-03-26 07:26:50 · 3 answers · asked by star wars freak 2

or have they not cracked it yet

2007-03-26 07:19:49 · 9 answers · asked by Anonymous

do yoou think that if they came up with something like that it would mean that the beam kills you and makes a fake you somewere else? and your soul is lost? i don't think a beam can make a soul? just a thought and yeah i'm puttting this in physics because of the soul issue?

2007-03-26 07:19:09 · 2 answers · asked by ♥lois c♥ ☺♥♥♥☺ 6

A wagon is coasting at a speed vA along a straight and level road. When ten percent of the wagon's mass is thrown off the wagon, parallel to the ground and in the foward direction, the wagon is brought to a halt. If the direction in which this mass is thrown is exactly reversed, but the speed of this mass relative to the wagon remains the same, the wagon accelerates to a new speed vB. Calculate the ratio vB/vA

the answer? = 2
how to get there? = NO CLUE

help? thanks a bunch

2007-03-26 07:15:59 · 1 answers · asked by lairdmanisland 1

Hi, I'm having a hard time working out these 4 problems on my review sheet. Could someone please help me the following problems and show me the steps or the formulas, our book in school is not any help-it's old? Thanks:) (Best Answer will be picked).

A 0.92Hz continous wave travels on a Slinky. If the wavelength is 0.68m, what is the speed of the wave?
____m/s

The force stretching a string with linear mass density 0.005kg/m is 113N. What is the speed of a wave on the string?
___m/s

If you are very far away from an object when it is hit, you often see the collision before you hear it. For example, lets say you are 1100m from a gun when it is fired.

a) How long will it take for you to see the gun fired?
____s
b) How long will it take for you to hear the gun fired?
____s
----
Sonar: Suppose you are fishing using your handy dandy new sonar. The sonar display tells you there is a school of fish 181m away. How long did it take the take the signal to travel round trip? __s

2007-03-26 07:00:06 · 4 answers · asked by Zalak 1

2007-03-26 06:42:31 · 5 answers · asked by sledhead121 1

Does any one know it in detail?

2007-03-26 05:52:46 · 11 answers · asked by Anonymous

2007-03-26 05:33:36 · 5 answers · asked by muhammad r 1

The puck moving with velocity v = 10 m/s hits the floor
at angle 45 deg and continues to move sliding on the
floor.

http://alexandersemenov.tripod.com/puck/index.htm

Coefficient of friction μ = 0.3; g = 9.8 m/s².

2007-03-26 05:32:35 · 2 answers · asked by Alexander 6

2007-03-26 05:27:46 · 1 answers · asked by Anonymous

If electron is released at the center of superconductive
shperical shell what will be its acceleration?

2007-03-26 05:27:10 · 1 answers · asked by Alexander 6