Physics - May 2007

A flywheel of mass 40kg and radius 2m, positioned so that it rotates about an horizontal axis...?

is initially at rest. A length of light string is wrapped around the flywheel with a mass of 2kg attached to the free end. The mass is initially 4m above the ground. As the mass drops, the string unwinds and the flywheel accelerates.

The question states:

At the instant the attached mass reaches the ground, a pair of brake blocks are applied and the flywheel is brought to rest in 0.2s. Given that the brake blocks are located 1.6m from the centre of gravity of the flywheel, and the coefficient of friction is 0.9, determine the normal reaction force between the flywheel and each brake block.

Usually if use of moment of inertia is required, it will quote the equation needed, however in this instance it hasn't. Is there anyway to do this without?

Thanks :)

2007-05-24 21:33:29 · 1 answers · asked by Anonymous

A playground carousel is free to rotate about its center on frictionless bearings. The carousel has an angular speed of 3.14 rad/s, a moment of inertia of 124 kg m^2 and a radius of 1.80m. A 40.0kg person, standing still next to the carousel jumps on very close to the outer edge. Find the resulting angular speed of the carousel and person.

I've been at this question forever....anyone who can answer this shall have my unending love and gratitude :P

2007-05-24 18:33:24 · 2 answers · asked by Anonymous

Vector A is 3.0 units in length and points along the poisitive x-axis; vector B is 4.0 units in length and points along a direction 150* from the positive x-axis. What is the magnitude of the resultant when vectors A and B are added?

a. 7.0
b. 6.7
c. 4.7
d. 2.1

If you can please plug in the numbers too...I tried figuring it out and Im getting a little confused

2007-05-24 16:45:12 · 2 answers · asked by Anonymous

Object A is a cylinder with the density of 0.8g/cubic centimeter and Object B is a flat rectangular object with the density of 1.2 g/cubic centimeter.
What will happen when the objects are placed in a container of water (water temp. = 4 degrees celcius)??

(a) Both objets will sink.
(b) Both objects will float.
(c) Object A will float and object B will sink.
(d) Object B will float and object A will sink.

i think the answers is (d), but I'm not sure whether the density or the shape of an object determines weather objects float/sink.

2007-05-24 14:41:44 · 2 answers · asked by ☮ 5

My science question for the day..any body kind enough to elaborate for me? Thanks a lotsa..

2007-05-24 14:33:36 · 3 answers · asked by Imaginarist... 1

A speeder passes a parked police car at 35.0 m/s. The police car starts from rest with a uniform acceleration of 2.88 m/s2.
(a) How much time passes before the speeder is overtaken by the police car?
_____s
(b) How far does the speeder get before being overtaken by the police car?
_____m
-Next question-
A rocket moves upward, starting from rest with an acceleration of 30.2 m/s2 for 8.00 s. It runs out of fuel at the end of the 8.00 s but does not stop. How high does it rise above the ground?
_____m
-Next question-
A ball is thrown vertically upward (assumed to be the positive direction) with a speed of 22.0 m/s from a height of 3.0 m.
(a) How high does the ball rise from its original position?
_____m
(b) How long does it take to reach its highest point?
_____s
(c) How long does the ball take to hit the ground after it reaches its highest point?
_____s
(d) What is the ball's velocity when it returns to the level from which it started?
_____m/s
Thanks

2007-05-24 14:32:15 · 1 answers · asked by Johnson 2

An ice sled powered by a rocket engine starts from rest on a large frozen lake and accelerates at +15.0 m/s2. At t1 the rocket engine is shut down and the sled moves with constant velocity v until t2. The total distance traveled by the sled is 5.30 103 m and the total time is 89.0 s.
Find tl.
_____s
Find t2.
_____s
Find v.
_____m/s
--------NEXT question-------
A parachutist descending at a speed of 10.0 m/s loses a shoe at an altitude of 50.0 m. (Assume the positive direction is upward.)
(a) When does the shoe reach the ground?
______s
(b) What is the velocity of the shoe just before it hits the ground?
______ m/s

2007-05-24 14:28:46 · 1 answers · asked by Johnson 2

What does the F ratio of a camera mean? I've seen stuff like F/4 or F/8 or F/12. What does that mean?

2007-05-24 12:09:30 · 2 answers · asked by Anonymous

2007-05-24 12:07:58 · 10 answers · asked by LeSsBrAiN 2

In the periodic table, we have nuclei weighing more than 200 with more than 100 protons in the nucleus. Is this the limit of how big an atomic nucleus can get? And why?

2007-05-24 11:24:23 · 7 answers · asked by misoma5 7

2007-05-24 11:24:19 · 10 answers · asked by smartbiz85 1

(0) The chunks of tea leaves sink in tea.

(a) If a cup of tea is placed in the center of rotating
catousel, where will the chunks of tea leaves congregate?

(b) If tea is stirred inside non-rotating teacup,
where will the chunks of tea leaves congregate?
(this one can be easily verified if you care to
make a trip to cafeteria).

2007-05-24 11:18:47 · 3 answers · asked by Alexander 6

I would just like to know if I have a function of position x=3t-3t^2+t^3, with a mass m=3kg. Then all I would have to do is take my dv/dt function times my mass and then integrate it from x(0) to my X(4) to get my work done over that interval. I get 720J as my answer. Does that make since?

2007-05-24 10:42:03 · 3 answers · asked by Michael M 4

Can you give me an example

2007-05-24 09:30:10 · 9 answers · asked by latina218bella 1

Ok, let's say you're driving down the road in your car, and there's a fly in the car that's just kinda flying around the same general little area. How come the fly doesn't have to keep flying forward in order to keep up with the vehicle? Wouldn't the fly eventually be hit by the back of the vehicle?

2007-05-24 09:15:01 · 6 answers · asked by GK Dub 6

Are there any differences in curriculum?

2007-05-24 09:10:04 · 3 answers · asked by electrical engineer 3

In one-dimensional world (2-D relativistic space-time)
astronomer observs UFO flying by at speed 1.5c.

What is the speed of astronomer as seen by the
pilot of the UFO?

2007-05-24 08:56:52 · 3 answers · asked by Alexander 6

If so, would everything still space out evenly at absolute zero? Would gasses be able to be unevenly spaced, clump up and turn into a pile of atoms and particles once they quit wiggling?

2007-05-24 08:56:37 · 6 answers · asked by saralizzy1981 3

2007-05-24 07:02:41 · 8 answers · asked by amany e 1

If electrostatic currents create electromagnetic fields, can an outside source interpret these fields to gain a partial understanding of its source, hence partially decode the thought that originated the waves?

If so, wouldn't this mean that anyone would be able to interpret this wave at a rate equal to the speed of light?

2007-05-24 07:00:29 · 4 answers · asked by the_Bo0geYmaN 2

2007-05-24 06:55:34 · 3 answers · asked by kb 1

On a smaller scale...the way that birds fly south for the winter, due to their "built in compass" or manetite. Can human's tap into that energy and if so, can we reverse the polarities and what possibilities could we attain?

2007-05-24 06:34:26 · 6 answers · asked by Michellle 1

I have a question on the dopplers effect that i'd like all you physics geniuses to help me out with, question is: the doppler effect using ultrasonic waves of frequency 2,50 x 10^6 hz is used to moniter the heartbeat of the fetus. The maximum speed of the surface of the beating heart is,0.300 m/s. Calculate the maximum beat frequency observerd. Assume that the speed of sound in the tissue is 1,54 x 10^3 m/s.

2007-05-24 06:03:22 · 1 answers · asked by Lerato M 1

I was sitting within a few inches of a Digital clock connected to the 120 V. There is a transformer which will send electomagnetic radiation. Somebody advised me to move farther as it is harmful to the body. Please let me whether it is true. If so wha damage it can do. Thanks

2007-05-24 06:03:05 · 5 answers · asked by rk 2

2007-05-24 05:45:11 · 9 answers · asked by goring 6

2007-05-24 05:28:33 · 6 answers · asked by James 1

What things did he invent, when was he born, things about him, what made him a really good person etc.

2007-05-24 05:25:01 · 12 answers · asked by Anonymous

You can simply answer it by stating the familliar equation torque=Fr.
But it is just a mathematical expression.
I expect a more intuitional answer.
Thx in advance.

2007-05-24 05:04:31 · 3 answers · asked by Anonymous

constant.
1) 2 m
2) 4 m
3) 8 m
4) Insufficient data

2007-05-24 04:56:22 · 2 answers · asked by margoretewhitfield 1

2007-05-24 04:42:36 · 12 answers · asked by goring 6