Physics - November 2007

A force of 27.0 N is required to start a 3.9 kg box moving across a horizontal concrete floor.
(a) What is the coefficient of static friction between the box and the floor?

(b) If the 27.0 N force continues, the box accelerates at 0.50 m/s2. What is the coefficient of kinetic friction?

2007-11-12 14:39:14 · 2 answers · asked by roofchelsea 1

(a) What is the speed of the transverse string waves?
(b) What is the tension?
(c) What are the wavelength and frequency of the sound wave in air produced by vibration of the string? The speed of sound in air at room temperature is 340 m/s.

What I did didn't work so now I'm confused. Help me out if you can. Thanks!

2007-11-12 14:39:07 · 2 answers · asked by anjelle_2 1

please i would love to know!!! :D

2007-11-12 14:29:43 · 1 answers · asked by coastguardluvr 2

Three objects of equal mass (m) each are located on a corner of a square length L
What is the gravitational field on the fourth corner with no mass due to theses objects?


m1---------------m2
|..........................|
|..........................|
|..........................|
X-------------------m3

{<-------L------->}

2007-11-12 14:29:03 · 1 answers · asked by MeNeedHelp 2

A pendulum clock with a brass suspension
system is calibrated so that its period is 1 s at 13C.
If the temperature increases to 39C, by
how much does the period change in units of s?

How much time does the clock gain or lose in
one week in units of s?

2007-11-12 14:27:44 · 1 answers · asked by ? 1

You obtain a mean force reading of 2.33 N pulling on an object with a force sensor. During this time the object moves with uniform motion. Then you suspend the object from the hook of the sensor and obtain a reading of 12.2 N. Assuming the force sensor was properly zeroed, what is the coefficient of kinetic friction between the object and the surface?

2007-11-12 13:48:31 · 2 answers · asked by Hades Lee 2

Well i am back for some more questions.
I figured out that there is a relationship between mass and volume only when the density(object) is the same.

So now, in my experiment i have to use sample aluminum.
It is just like a round water droplet and NOT the log cylindrical samples.

Ok so my question is:

Lets say i start out with 5 samples i record the data. THEN i add 5 more samples. Record the data. And so on. Will this still show that there is a realtionship between mass and volume. A proportional relatiosnhiop?

2007-11-12 13:45:37 · 2 answers · asked by Anonymous

The following problem is a standard problem found in many physics text books. A block of mass M is at rest on a horizontal frictionless table. It is attached to a rigid support by a spring of constant k. A clay pellet having mass m and velocity v strikes the block from the opposite side that the spring is attached to.

(a) Determine the velocity of the block immediately after the collision.
(b) Determine the amplitude of the resulting simple harmonic motion. In order to solve this problem you must make a number of simplifying assumption; some are stated in the problem and some are not. First, solve the problem as stated.
(c) Discuss the approximations you had to make in order to solve the problem. (There are at least five.)

Explain your work. Thanks! :)

2007-11-12 13:31:20 · 1 answers · asked by Anonymous

The human heart provides about 1 to 10 watts of power to circulate blood through the body. A 9.6 volt, 2.6 amp-hour rechargeable battery is used for some cordless electric drills. For 100 percent efficient conversion of electrical energy into blood pumping work, estimate how long one of these rechargeable batteries qould last when 5 watts of power is consumed. Recall that 1 J/sec = 1 W = 1 A * 1 V

2007-11-12 13:18:32 · 2 answers · asked by ShanaReynolds 1

Im confused! I want to use my gel cell small light weight 12 volt 7ah/20h battery for my 45 amp electric outbord if my calculations are correct then 7ah multiplyed by 20hour equals 140 amphere battery,and if my electric outboard draws constint 45 amps than my 7ah/20h battery should last 3.11 hours (45amps divide 20 hours) equals 3.11 hours (AM I CORRECT IF NOT WHY) THANKYOU FOR YOUR HELP...

2007-11-12 13:09:51 · 2 answers · asked by Anonymous

If I have a ramp that is 0.285m long at an angle of 17degrees, and a final velocity of 2.38m/s, how can i get the initial velocity????

2007-11-12 13:08:40 · 1 answers · asked by Emma G 1

An electron movies with a speed of .600c. what is its momentum? the answers is 2.05x10^-22 Kg. m/s
I only know how to get gamma.

2007-11-12 13:07:36 · 3 answers · asked by mastersource2005 5

when all the info i have is amount Kinetic energy and the momemtum of the object

i know that KE=1/2m*v^2
but i don't have the mass. boo.

2007-11-12 13:02:51 · 1 answers · asked by *~JeS~* 5

You are to design a rotating cylindrical axle to lift 800-N buckets of cement from the ground to a rooftop 78.0 m above the ground. The buckets will be attached to a hook on the free end of a cable that wraps around the rim of the axle; as the axle turns, the buckets will rise.

A) What should the diameter of the axle be in order to raise the buckets at a steady 2.00 cm/s when it is turning at 7.5 rpm?

B) If instead the axle must give the buckets an upward acceleration of , what should the angular acceleration of the axle be?

I need some help with this question. What equations do I need to use? Thanks in advance for the help!

2007-11-12 12:47:25 · 1 answers · asked by nglennie_06 1

Smack a hockey puck on ice and it slides across the ice. The force that keeps it moving is:
A. gravity
B. friction
C. an interaction with the ice and the air
D. none of these

i thought it was B but i think im wrong. help please!!

2007-11-12 12:20:18 · 23 answers · asked by Anonymous

The question is that there is a amusement park and in one of the rides the riders stand with their backs against the wall of a spinning vertical cylinder. The floor falls away and the riders are held up by friction. The acceleration of gravity is 9.81m/s^2. The radius of the cylinder is 8m and I have to find the minimum number of revolutions per minute necessary when the coefficient of static friciton between a rider and the wall is 0.5. I have to answer is rev/min. I asked this question before but with different values but I don't get how the person got the answer (1/2π)*√(9.8/0.6*10) ≈ 0.064rev/s when I do it I get 0.2.

2007-11-12 12:15:15 · 1 answers · asked by glance 3

I have three questions i'm stuck on, please help.

1) A pool ball leaves a 0.60-meter high table with an initial horizontal velcity of 2.4m/s. Predict the time required for the pool ball to fall to the ground and the horizontal distance between the table's edge and the ball's landing location.

2)A soccer ball is kicked horizontally off a 22.0-meter high hill and lands a distance of 35.0 meters from the edge of the hill. Determine the initial horizontal velocity of the soccer ball.

3)A long jumper leaves the ground with an initial velocity of 12 m/s at an angle of 28-degress above the horizontal. Determine the time of flight, the horizontal distance, and the peak height of the long-jumper.

2007-11-12 12:05:31 · 1 answers · asked by That one guy 3

This energy is not available, the parts slow down and the clock shows time lost. A clock outside this frame of reference operates normally; this is in compete agreement with the theory of relitivity. An atomic clock will be affected in the same way, it operates with motion, the vibrating cesium crystal is still a form of motion. Science says that time and space came into being when the first sub atomic particle condensed from the singularity, what actully came into existance was motion and space, there was no time. It is motion and space that make the fabric of the universe, motion is the pulse of the universe. The theory of relativity has been ratified hundreds of times, an observer riding a beam of light would see the rest of the universe as being frozen because motion would not be detectable. Change the word, time, to motion,and nothing changes, everything becomes easier to understand, and time travel will no longer be a subject of discussion. H.B. Long.

2007-11-12 11:34:26 · 2 answers · asked by johnandeileen2000 7

Relativity states that, as matter approaches the speed of light, mass approaches infinity and time approaches zero. Time is defined as a period over which events take place. Events require motion, and motion requires matter and space. Without motion there can be no time. What separates motion from time? Matter and energy are two forms of the same thing. Motion and time are not. Time is needed to calculate speed and distance. Man solved this problem by inventing time, his clocks measure the length of a day in hours, minutes, and seconds. A clock is nothing but a machine. It is motion that regulates the length of our day and year, motion of the Earth around its axis and its path around the sun, this has nothing to do with time, it is all about motion. A clock contains matter, therefore it has mass. If you subject a clock to relitivistic speed, its mass will increase; under this condition the movement of its components will slow due to the increased energy required to overcome inertia,

2007-11-12 11:14:04 · 1 answers · asked by johnandeileen2000 7

In an experiment, I got a non-zero intercept for a graph of applied force versus normal force. What could explain this?

Thanks in advance for help.

2007-11-12 10:39:03 · 1 answers · asked by Emmy L 1

If raduis of round Earth is Re?

2007-11-12 10:31:34 · 3 answers · asked by Alexander 6

The fastest pitch recorded in MLB is thrown by nolan ryan. If this pitch was thrown horizantally, the ball would fall .809 meters by the time it reached home plate 18.3 meters away. How fast was Ryans pitch? The number 809 has a point in front of it, and 18 POINT 3, thnx a bunch guys, 10 points to anyone who gets this right?????????

2007-11-12 09:48:12 · 1 answers · asked by braber5 1

You have two lenses at your disposal, one with a focal length f1 = +31.9 cm, the other with a focal length f2 = -31.9 cm.

If you want to produce an image of the bulb that is enlarged by a factor of 3.00, how far from the wall should the lens be placed?
.............m

2007-11-12 09:47:48 · 1 answers · asked by ? 1

A body oscillates with simple harmonic motion according to the equation:

x = (6.0 m) cos [ ( 3 pi rad/s )t + pi/3 rad ]

At t = 2.0 s, what are (a) the displacement, (b) the velocity, (c) the acceleration, and (d) the phase of the motion?

Also, what are (e) the frequency and (f) the period of the motion?

Explain your work. Thanks! :)

2007-11-12 09:34:16 · 1 answers · asked by Anonymous

2007-11-12 09:20:05 · 4 answers · asked by thazel1040 1

2007-11-12 09:14:59 · 2 answers · asked by Up There 2

if you move mass from one side to the other keeping the total mass constant?
Gradually increase the mass of both sides?

2007-11-12 09:11:59 · 1 answers · asked by smarty 2

The moon ad earth are attracted to each other by gravitational force. Does the more-massive earth attract the moon with a greater force than the moon attracts the earth?

Don't really understand, please help.

2007-11-12 09:10:13 · 5 answers · asked by Up There 2

...show that the tension in the cable is 1.9 x 10^4 N

I'd really like to know how to work out tension, every time i've tried the answer's wrong. Help please!!

2007-11-12 08:59:17 · 2 answers · asked by Anonymous

A 2.2 kg purse is dropped from the top of the Leaning Tower of Pisa and falls 55 m before reaching the ground with a speed of 30 m/s. What was the average force of air resistance?
??N upward

2007-11-12 08:58:00 · 1 answers · asked by kdcheerldr 1