Physics - November 2007

14-13

please help, thanks!

2007-11-28 16:28:13 · 1 answers · asked by Kiwikahuna 2

Suppose that a string has a length L. What is the largest possible wavelength of a standing wave that can be supported by the string?

2007-11-28 16:03:14 · 2 answers · asked by Anonymous

An airplane is flying horizontally with speed 800 km/h (222 m/s) when an engine falls off. Neglect air resistance, and assume it takes 20 s for the engine to hit the ground.

How high is the airplane? in meters

How far horizontally does the engine travel while it falls? in meters

2007-11-28 15:57:45 · 1 answers · asked by joe s 1

Estimate the pressure exerted on a floor by the following.
(a) a 46 kg model standing momentarily on a single spiked heel (area = 0.06 cm2)

2007-11-28 15:56:42 · 3 answers · asked by Anonymous

Assume: The length of the athlete's arm is included in the length given for the chain below.

An athlete whirls a 6.81 kg hammer tied to the end of a(n) 1.3 m chain in a horizontal circle. The hammer moves at a rate of 1.47 rev/s.

a) What is the centripetal accelaration of the hammer? (in m/s^2)

b) What is the tension in the chain? (in N)

2007-11-28 15:53:01 · 1 answers · asked by ? 2

A motor having an efficiency of 88% operates a crane having an efficiency of 42%. With what constant speed does the crane lift a 410kg crate of machine parts if the power supplied to the motor is 5.5kW?

Power=Force*Velocity
so
5.5=velocity*force
how do you find force?

2007-11-28 15:50:38 · 5 answers · asked by Anonymous

The asteroid Ceres has a mass of 6.769*10^20 kg and a radius of 478.3 km.

a.) What is g on the surface? The value of gravitational constant is 6.67259*10^-11.

b.) How mush would an 85.4 kg astronaut weigh on this asteroid? (in units of N)

2007-11-28 15:46:07 · 2 answers · asked by ? 2

(1) dQ/dt = -Q/RC
(2)Q=Qoe^-t/RC note:Qo is the initial charge.

For equation 2 is called the solution, because when Q(t) is plug into equation 1, the left side will equal to the right side.

How do i demonstrate that RC has the dimensions of time?

2007-11-28 15:40:11 · 1 answers · asked by dav s 2

pls.explain!thank you..=)

2007-11-28 15:34:31 · 5 answers · asked by rexie13 1

Suppose you lived on the moon. Suppose the earth was directly over your head. How long would it be before you would see the earth set?

a) one day (one earth day, 24 hours)
b) one-fourth of a day (6 hours)
c) one month (the time it takes the moon to orbit the earth)
d) one-fourth of a month
e) you would never see the earth set

2007-11-28 15:06:36 · 3 answers · asked by ? 6

2 beads of mass m and charge q.
when placed in a hemispherical bowl of radius R with a frictionless, nonconducting walls, the beads move, and at equilibrium they are a distance R apart. Determine the charge on each bead.


____________/\....
___________/__\...
__________/____\
_________/______\
________/________\
_______/__________\
______/____________\
m [bead]=======[bead]m

the diagram is in an equilateral triangle ignore the "_"
so it will be R on each side of the triangle and the two beads m , m on the left and right side on bottom.
and ofcourse this triangle is inscribed in a semi sircle.. where the beads are the only parts of the triangle touching the semi sircle and the top of the semicircle is empty space.


The answer in the book is R(mg/[(k)(sqrt(3])^1/2 i tried forever and cant figure it out
Thanks

2007-11-28 15:04:14 · 1 answers · asked by MeNeedHelp 2

2007-11-28 14:47:16 · 6 answers · asked by Anonymous

car on cruise control is headed for a cliff at 35m/s leaves the (horizontal) edge, and strikes the ground below at 2.3 seconds.
a. What is the horizontal displacement- the range- of the car?
b. What is the horizontal velocity of the car?
c. What is the vertical velocity of the car?

2007-11-28 14:43:29 · 1 answers · asked by Anonymous

How would I figure out the calculated image distance and size when using a light source and lens? I am given the object distance and size and by using a graphical approach, I have the measured image distance and size.
Would this be correct: 1/distance of object + 1/distance of image= 1/focal point
I'm just not getting this because I get fractions and I was told to find the reciprocal. The numbers I get just doesn't make much sense.

2007-11-28 14:29:45 · 1 answers · asked by Elizabeth W 1

Basically, if you are conducting the Faraday experiment where you slide a magnet through a coil of wires, but, at the same time, there is already electricity flowing through the wire, then what happens. What would happen to the magnetic field being formed by the electricity flowing the coil, could it possibly spread? If anything does happen, will it continue to happen if the magnet is places in a non moving position or will it only happen in the presence of a moving magnetic field?

2007-11-28 14:15:20 · 1 answers · asked by megamak93 1

What is the speed of this wave?

2007-11-28 13:57:02 · 4 answers · asked by Anonymous

2007-11-28 13:33:33 · 1 answers · asked by Anonymous

A 0.446-kg puck, initially at rest on a frictionless horizontal surface, is struck by a 0.313-kg puck that is intitially moving along the x-axis with a velocity of 3.18 m/s. After the collision, the 0.313-kg puck has a speed of 2.18 m/s at an angle of 37 degrees to the positive x-axis.

(a) Determine the velocity of the 0.446-kg puck after the collision.

(b) Find the fraction of the kinetic energy lost in the collision

i got 1.44 m/s as the velocity but that answer is wrong i dont know what i did wrong

2007-11-28 13:29:02 · 1 answers · asked by njbadboy4life2005 3

Fx=kx
Fx is force applied to Spring
k is constant (N/m)
x is change in length of the spring

2007-11-28 13:21:23 · 2 answers · asked by lozter 1

an object is hit, giving it an initial velocity of 4 m/s. If the coefficient of kinetic friction between the ice and puck is 0.05, how far will the puck slide before stopping?
***please show free body diagrams and equations used, thanks!!!!!

2007-11-28 13:20:20 · 1 answers · asked by cooldude123 2

The ball is hit at an angle of 38.7 degrees to the horizontal, and air resistance is negligible. Assume the ball is hit at a height of 1.2m above ground.
what is the initial speed of the ball? (m/s)
How much time does it take for the ball to reach the wall? (s)
Find speed of ball when it reaches the wall. (m/s)

2007-11-28 13:10:43 · 1 answers · asked by Anonymous

Two cars, both of mass m, collide and stick together. Prior to the collision, one car had been traveling north at speed 2v, while the second was traveling at speed v at an angle phi south of east (as indicated in the figure). After the collision, the two-car system travels at speed v_final at an angle theta east of north.

What is the angle theta with respect to north made by the velocity vector of the two cars after the collision?

Express your answer in terms of phi. Your answer should contain an inverse trigonometric function.

I was trying to solve it by breaking it down the components in x & y direction.

so i did in x-direction: (2m)v_i cos (0) - (2m) 2v_i sin (theta) = (2m)v_i tan (theta)

Now i used the formula m1v1+m2v2= (m1+m2)v3

Since this is inelastic i thought the 2nd direction would be subtracted since energy isn't conserved.

Please help i tried to do the algebra and im confused. Am i even supposed to be using this equation?

2007-11-28 13:08:47 · 4 answers · asked by Anonymous

Uranus requires 84 years to circle the sun. Find Uranus' orbital radius as a multiple of Earth's orbital radius.

What formula do I need to use and what does this question actually mean? Thanks!

2007-11-28 12:32:08 · 1 answers · asked by Need4Speed 2

A nuclear power plant has a power output of 1000 MW and operates with an efficiency of 34%. If excess heat is carried away from the plant by a river with a flow rate of 1.0 x 10^6 kg/s, what is the rise in temperature of the flowing water?
Answer in °C.

2007-11-28 12:26:45 · 1 answers · asked by Tim R 1

The ball strikes the ground at the point 125 m from the base of the building. The acceleration of gravity is 9.8

I know the time the balls in motion is 2.14

I just need to knowthe initial velocity of the ball.

Can someonen help?

2007-11-28 12:25:09 · 1 answers · asked by The Problem Solver 3

[just a short explanation to help me understand]

2007-11-28 12:22:33 · 1 answers · asked by cigar_muffin 1

2007-11-28 12:20:34 · 4 answers · asked by Anonymous

an astronaut lands on an earthlike planet and drops a small lead ball with a mass of 76.5g from the top of her spaceship.the point of release is 16m above the surface of the planet & the ball takes 2.2 s to reach the ground. the astronaut's mass on earth is 68.5kg. her wieght on th planet is?

2007-11-28 12:01:09 · 2 answers · asked by Anonymous

doug hits a hockey puck, giving it an initial velocity of 6.0 m/s. if the coefficient of kinetic friction between ice and puck is 0.02, how far will the puck slide before stopping?

2007-11-28 11:57:23 · 1 answers · asked by Anonymous

a man pulls a sled at a constant velocity across a horizontal snow surface. if a force of 60N is being applied to the sled rope at an angle of 53 degrees to the ground, what's the force of friction between the sled and snow?

2007-11-28 11:53:55 · 2 answers · asked by Anonymous