Physics - October 2007

Take free fall acceleration to be = 9.80 .
A wooden rod of negligible mass and length 75.0 is pivoted about a horizontal axis through its center. A white rat with mass 0.480 clings to one end of the stick, and a mouse with mass 0.200 clings to the other end. The system is released from rest with the rod horizontal.

2007-10-28 11:12:54 · 1 answers · asked by Anonymous

Please Help this is urgent!! Anyone know how to prove that? Is it that I just pick a whole bunch of random degrees and say look this is all I have to prove it. please help!!

2007-10-28 10:59:34 · 2 answers · asked by The Optimist 2

1. A block of mass m=1.20 kg is stacked on top of a block of mass M=3.20 kg and the two move together on a horizontal surface with a constant acceleration of magnitude a=4.04 m/s^2 pointing to the right under the influence of an external horizontal force of manitude F0=40.3N which is applied to mass M. The coefficient between mass m and mass M is (mu)=0.780. The coefficient of kinetic friction between block m and block M is not given. The coefficient of kinetic friction between block M and the horizontal surface is also not given.

a. What is the magnitude of the force of friction exerted by block M on m?

b. What is the magnitude of the force of friction exerted by the horizontal surface on block M?

Please show your work :)

2007-10-28 10:54:38 · 1 answers · asked by carbonatedcolor 2

3 blocks are in contact with each other on a frictionless horizontal surface. A 553 N horizontal force is applied to the block with mass of 3.6 kg.

Block A = 3.6 kg
Block B = 5.8 kg
Block C = 6.8 kg

a) What is the magnitude of the force between the block with mass of 5.8 kg and 6.9 kg? Answer in N.
b) What is the magnitude of the force between the block with mass 3.6 kg and 5.8 kg? Answer in N.

Thank you!!!

2007-10-28 10:53:57 · 1 answers · asked by Melissa 1

Right here: http://answers.yahoo.com/question/index?qid=20071028142836AAXwOF5&r=w#TIZXJGPqIlOC7.hDyi3Z
This is in the religion section, I know, but a lot of science questions are improperly posted there. It would be nice if he could get some scientific answers.

2007-10-28 10:40:01 · 2 answers · asked by JavaGirl ~AM~ 4

I do physics for my A levels and i would like to know about any fun type of engineering. help please??

2007-10-28 10:30:44 · 7 answers · asked by Anonymous

An athlete on a trampoline leaps straight up into the air with an initial speed of 9.0 m/.s. Find (a) the maximum height reached by the athlete relative to the trampoline (b) the speed of the athlete when she is halfway up to her maximum height.

2007-10-28 09:50:57 · 1 answers · asked by Mika 2

Can you tell how large a sample she made? How?

2007-10-28 09:46:24 · 1 answers · asked by Anonymous

Body A of mass M has an original velocity of 6.2 m/s in the +x-direction toward a stationary body (body B) of the same mass. After the collision, body A has velocity components of 1.1 m/s in the +x-direction and 2.1 m/s in the +y-direction. What is the magnitude of body B's velocity after the collision?
________m/s

Please tell me HOW to do this problem, I tried and got 3 but that is not right.. please explain how to do this!

2007-10-28 09:44:35 · 1 answers · asked by ? 2

a crate of mass 10.0 kg is pulled up a rough incline with an initial speed of 1.50 m/s. The pulling force is 100N parallel to the incline, which makes an angle of 20.0 degrees with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 5.00 m. (1) How much work is done by gravity? (b) how much mechanical energy is lost due to friction? (c) what is the change in kinetic energy of the crate? (e) what is the speed of the crate after being pulled 5.00 m?

2007-10-28 09:41:07 · 2 answers · asked by Mika 2

If my cell phone battery is completely dead, how much will it cost to charge it (if the battery is 2000 MaH?) Basically, how many 'units' of electricity will it take to fully charge the phone?

2007-10-28 09:35:15 · 2 answers · asked by Johnny 3

I've been wondering this for a little while now.
Does the pressure of the water bring it up?
Or something else?

2007-10-28 09:27:58 · 4 answers · asked by Anonymous

A 280 g block on a 52.0 cm-long string swings in a circle on a horizontal, frictionless table at 85.0 rpm.

What is the speed of the block?
What is the tension of the string?

2007-10-28 09:18:12 · 1 answers · asked by Anonymous

how can you decide which is stronger between gravity and electricity. aren't they governed by kqq'/r^2 and Gmm'/r^2.... so which will win is solely determined by the ratio of kqq' to Gmm'. shouldn't the real question be which tends to be larger given typical matter... I mean... electron to electron obviously electricity wins over gravity.
neutron to neutron gravity wins right, since there is no electric force.
what's the weak force anyway?
can anyone pt. me to a link or have a good discussion on the subject?

2007-10-28 08:57:03 · 1 answers · asked by keyahnoo 2

I need this for a short thesis, but I have no time to find the appropriate literature. Thanks for the help. :)

2007-10-28 08:04:01 · 2 answers · asked by Aurora 4

A rotational axis is directed perpendicular to the plane of a square and is located as shown in the drawing. Two forces, 1 and 2, are applied to diagonally opposite corners, and act along the sides of the square, first as shown in part a and then as shown in part b of the drawing. In each case the net torque produced by the forces is zero. The square is one meter on a side, and the magnitude of 2 is 3 times that of 1. Find the distances a and b that locate the axis. Note that a and b are not drawn to scale.

I'm not sure where to begin with this question. Can someone give me some tips? I'd greatly appreciate it.

Thanks.

2007-10-28 07:59:02 · 1 answers · asked by Anonymous

A centrifuge in a medical laboratory rotates at an angular speed fo 3,600 rev/min. When switched off, it rotates throught 50.0 revolutions before coming to rest. Find the constant angularr acceleratioin of the centrifuge?

COULD SOMEONE PLEASE HELP ME ON THIS PROBLEM. I TRIED WORKING IT OUT, BUT MY ANSWER IS DIFFERENT FROM THE BOOK. PLEASE SHOW ME THE RIGHT WAY AND THE ANSWER. THANK YOU

2007-10-28 07:54:34 · 2 answers · asked by markeesha h 1

Large objects also have wave properties in addition to particulate properties, but the wave length in large objects are so small that we cannot detect it.

1. How do we detect wavelength? Do we detect them through sight, touch etc?
2. Why can't we detect small wavelength?

2007-10-28 07:50:15 · 1 answers · asked by ashlee052690 1

A 1400 kg blue convertible is traveling south, and a 2080kg red SUV is traveling west. The total momentum of the system consisting of the two cars is 8500 kg.m/s directed at an angle 63.0 west of south.

2007-10-28 07:32:00 · 3 answers · asked by Natiphy2007 1

Name Something that you "_eat_" that doesn't get it's energy from the sun. It can only be one thing.

For example: Gum can't be one because gum is from cows and cows eat grass and grass get it's energy from the sun.

Or...: fish can't be one either because fish eat algae and algae is a plant and get's it energy from the sun.

you know what I mean????

2007-10-28 07:09:45 · 7 answers · asked by Animosity 3

Show that the SI units of the force constant of a spring can be written as Kg/s^2?

2007-10-28 07:07:43 · 5 answers · asked by stang16041 1

2007-10-28 06:30:54 · 5 answers · asked by MeDIGURU 1

A ditch 2.29 m wide crosses a trailbike path. An upward incline of 15.5 degrees has been built up on the approach so that the top of the incline is level with the top of the ditch. What is the minimum speed (in m/s) at which a trailbike must be moving to completely clear the ditch? (Add 1.52 m to the range for the back of the bike to clear the ditch safely.)

2007-10-28 06:30:24 · 1 answers · asked by ags101 2

2007-10-28 06:19:46 · 30 answers · asked by Anonymous

Counting the length L and the width d of an oblong square we find the following numbers:

L: 24.25 / 24.26 / 24.22 / 24.28 / 24.24 / 24.25 / 24.22 / 24.26 / 24.23 / 24.24

d: 50.36 / 50.35 / 50.41 / 50.37 / 50.36 / 50.32 / 50.39 / 50.38 / 50.36 / 50.38

Measure the surface of the oblong square and the "mismeasure" with 2 ways:

a) From Li, di calculate δL and δd and S and δS.
b) From Li and di, calculate Si and then δS

Please help me with this, and I do not want just the answer, I want the whole solution as well so as to understand it.. Thanks in advance!

2007-10-28 06:08:59 · 1 answers · asked by hoot_dude 2

A model rocket is fired vertically upward from rest. Its acceleration for the first three seconds is a(t) = 60t at which time the fuel is exhausted and it becomes a freely "falling" body. Fourteen seconds later, the rocket's parachute opens, and the (downward) velocity slows linearly to -18 ft/s in 5 s. The rocket then "floats" to the ground at that rate.

a) At what time does the rocket reach its maximum height?

What is that height?

b) At what time does the rocket land?

2007-10-28 06:04:22 · 2 answers · asked by ark_in_space 1

Hello everyone.

I am not very sure of this proof for my homework. If someone can help me I would be very happy.

-Police radar detects the speed of a car. Microwaves of a precisely known frequency are broadcast toward the car. The moving car reflects the microwaves with a Doppler shift. The reflected waves are recieved and combined with an attenuated version of the transmitted wave. Beats occur between the two microwave signals. The beat frequency is measured.
For an electromagnetic wave reflected back to its source fomr a mirror approaching at speed v, show that the reflected wave has a frequency:
f = fsource * (c+v) / (c-v)

O_O

2007-10-28 05:44:55 · 1 answers · asked by Park Jung Suk 1

A loaded ore car has a mass of 950 kg and rolls on rails with negligible friction. It starts from rest and is pulled up a mine shaft by a cable connected with a winch. The shaft is inclined at 30.0 degrees above the horizontal. The car accelerates uniformly to a speed of 2.20 m/s in 12.0 seconds and then continues at a constant speed. (a) What power must the winch motor provide when the car is moving at a constant speed? (b) What maximum power must the motor provide? (c) What total energy transfers out of the motor by work by the time the car moves off the end of the track, which is of lenght 1,250 m?

2007-10-28 05:20:34 · 2 answers · asked by lgd1356 1

who discovered silicon?

2007-10-28 05:03:56 · 4 answers · asked by ciaramichelle93 1

2007-10-28 05:02:22 · 5 answers · asked by Anonymous