Physics - October 2007

2007-10-30 02:31:13 · 6 answers · asked by Shiva S 1

2007-10-30 02:01:00 · 5 answers · asked by Tony Y 2

Wire is often delivered wrapped on a large cylindrical spool. Suppose such a spool is supported by resting on a horizontal metal rod that is pushed through a hole that runs through the center of the spool. A worker is pulling some wire off the spool by exerting a force on it something like is shown in the diagram at the right. (If you have ever bought wire in a hardware store, this is the way they usually store and dispense it.)

Suppose the spool rotates on the rod essentially without friction. The spool is approximately a uniform cylinder with a mass of 50 kg and a radius of 30 cm. The worker pulls on the wire for 2 seconds with a force of 30 N. At the end of the 2 seconds he immediately clamps on a brake which very quickly stops the spool's rotation. Just before he put the brake on, how fast was the spool rotating? How much wire did he pull off the spool?

2007-10-30 01:55:47 · 2 answers · asked by Anonymous

The flywheel of a steam engine runs with a constant rotational velocity of 150 rev/min. When the steam is shut off, the friction of the bearings and of the air stops the wheel in 2.2 h. (a) What is the constant rotational acceleration, in revolutions per minute-squared, of the wheel during the slowdown?

(b) How many rotations does the wheel make during the slowdown?

(c) At the instant the flywheel is turning at 75 rev/min, what is the tangential component of the translational acceleration of a flywheel particle that is 50 cm from the axis of rotation? (d) What is the magnitude of the net translational acceleration of the particle in (c)?

Explain your work. Thanks! :)

2007-10-30 01:50:04 · 1 answers · asked by Anonymous

The flywheel of a steam engine runs with a constant rotational velocity of 150 rev/min. When the steam is shut off, the friction of the bearings and of the air stops the wheel in 2.2 h. (a) What is the constant rotational acceleration, in revolutions per minute-squared, of the wheel during the slowdown?

(b) How many rotations does the wheel make during the slowdown?

(c) At the instant the flywheel is turning at 75 rev/min, what is the tangential component of the translational acceleration of a flywheel particle that is 50 cm from the axis of rotation? (d) What is the magnitude of the net translational acceleration of the particle in (c)?

Explain your work. Thanks! :)

2007-10-30 01:47:53 · 2 answers · asked by Anonymous

question
A student uses an audio oscillator of adjustable frequency to measure the depth of a water well. The student hears two resonances at 51.5Hz and 60.0Hz. How deep is the well ?

Can you give me an explanation and an answer .. the answer should be 21.5m

I don't know where to start and where to finish with this question.. the txt book is not helping .. just half of a page .. so am basically stuck.. being at it for 3 hrs...
Thank you...

2007-10-30 01:28:45 · 2 answers · asked by Anonymous

Why is this?
Shouldn't the steel rods expand due to heat?

2007-10-29 23:58:01 · 7 answers · asked by samoolian 2

2007-10-29 19:39:04 · 9 answers · asked by Anonymous

on the surface of Jupiter?

2007-10-29 19:32:29 · 3 answers · asked by Xquisite Shawtey 1

given by v(t) = -1 + e^(1-t).
(a) Find the acceleration of the particle at time t = 3
(b) Is the speed of the particle increasing at time t = 3? Give a reason for your answer.
(c) Find all values of t at which the particle changes direction. Justify your answer.
(d) Find the total distance traveled by the particle over the time interval 0 is less than or equal to t is less than or equal to 3.

2007-10-29 18:35:10 · 3 answers · asked by help! 1

A 2.5 kg cart, moving along the x-axis with constant acceleration, crosses the origin at t=0 with velocity 4.0 m/s to the left. What must be the net force on the cart if some time later it is moving to the right at velocity 12 m/s at position +10 m?
please asap
thank you

2007-10-29 18:24:10 · 1 answers · asked by Anonymous

2007-10-29 18:07:09 · 2 answers · asked by Anikin 1

A bullet of mass 12g strikes a solid surface at a speed of 300 m s^ -1. The bullet penetrates to a depth of 3.0 cm.

(i) Calculate the average force resisting the motion of the bullet in the solid.

The solution:

F = ma
= 0.012 * (-1.5) * 10^6
= -18 000 N

Average resistive force is 18 000 N

Why is it that the force is positive? Why can't we just leave it as negative? Why must we must change it to positive?

2007-10-29 17:59:29 · 3 answers · asked by Anonymous

If a CD rotates at 500 rpm while the last song is playing, and then spins down to zero angular speed in 2.60 s with constant angular acceleration, what is the magnitude of the angular acceleration of the CD, as it spins to a stop?

2007-10-29 17:20:22 · 1 answers · asked by KT 1

The sun rotates every 200 million years about the center of the milky way galaxy at a distance of 30,000 ly from the center. What is the mass of the galaxy and what assuptions were made?

2007-10-29 16:59:59 · 1 answers · asked by h_oboe 2

2007-10-29 16:58:04 · 1 answers · asked by citruspitcher04 1

You are conducting an experiment inside a train car that may move horizontally along rail tracks. A load is hung from the ceiling on a string. The load is not swinging, and the string is observed to make a constant angle of 45 degrees with the horizontal. No other forces are acting on the load. which of the following statements are correct?

A.The train is an inertial frame of reference.
B.The train is not an inertial frame of reference.
C.The train may be at rest.
D.The train may be moving at a constant speed in a straight line.
E.The train may be moving at a constant speed in a circle.
F.The train must be speeding up.
G.The train must be slowing down.
H.The train must be accelerating.

2007-10-29 16:50:15 · 1 answers · asked by larryman210 1

2007-10-29 16:41:04 · 1 answers · asked by Indi 2

The flywheel of a steam engine runs with a constant rotational velocity of 150 rev/min. When the steam is shut off, the friction of the bearings and of the air stops the wheel in 2.2 h. (a) What is the constant rotational acceleration, in revolutions per minute-squared, of the wheel during the slowdown?

(b) How many rotations does the wheel make during the slowdown?

(c) At the instant the flywheel is turning at 75 rev/min, what is the tangential component of the translational acceleration of a flywheel particle that is 50 cm from the axis of rotation? (d) What is the magnitude of the net translational acceleration of the particle in (c)?

Explain your work. Thanks! :)

2007-10-29 16:39:48 · 1 answers · asked by Anonymous

A boy throws a rock horizontally from an elevated position 16 feet above the ground (perhaps from a cliff's edge). The rock travels a horizontal distance of 40 feet. How fast did the boy throw the rock? (Again, consider time.)

a) 16 ft/s
b) 40 ft/s
c) 43 ft/s
d) 56 ft/s
e) Cannot be solved with the information given

2007-10-29 16:32:21 · 3 answers · asked by ? 6

limerick or haiku

2007-10-29 16:31:27 · 2 answers · asked by vy a 1

Imagine a frictionless pulley (a solid cylinder) of unknown mass M and radius r = 0.22 m is used to draw water from a well. A bucket of mass m = 1.46 kg is attached to a cord wrapped around the cylinder. A bucket starts from rest at the top of the well and falls for t = 2.01 s before hitting the water h = 7.48 m below the top of the well. Neglect the mass of the cord.

Find angular acceleration, and tension of the cord

2007-10-29 16:23:48 · 1 answers · asked by DUTS 1

be specific...

2007-10-29 15:43:35 · 3 answers · asked by Anonymous

There are two blocks hanging on a pulley attached by a cord. One block has a mass M = 500 g, the other has mass m = 460 g, and the pulley, which is mounted in horizontal frictionless bearings, has a radius of 5.00 cm. When released from rest, the heavier block falls 75.0 cm in 5.00 s (without the cord slipping on the pulley).

(a) What is the magnitude of the blocks’ acceleration?

What is the tension in the part of the cord that supports (b) the heavier block, and (c) the lighter block?

(d) What is the magnitude of the pulley’s rotational acceleration?

(e) What is its rotational inertia?

Explain your work. Thanks :)

2007-10-29 15:37:37 · 1 answers · asked by Anonymous

Which one of the following would have the most momentum- a charging elephant, a jumbo jet sitting on the runway, or a baseball traveling at 100 km/h? Explain.

2007-10-29 15:36:38 · 10 answers · asked by fabulous! 1

cuz someone told me he said something like it would be like that movie "butterfly effect" where no matter your intention, something worse would happen...

2007-10-29 15:15:48 · 3 answers · asked by Whole 4

Galileo the 1500s mathematitian

2007-10-29 14:55:20 · 3 answers · asked by ism 2

Can anyone help me with this quesion?
Which one is higher and which one applies during a skidding car?

2007-10-29 14:54:46 · 2 answers · asked by Anonymous

* all i really need to know is if plasma has more energy than gas*

2007-10-29 14:44:29 · 2 answers · asked by Erick H 1

im doing a project and i need the answer to this question thanks. The clearer you explain the better.

2007-10-29 14:33:46 · 2 answers · asked by Anonymous