Physics - November 2007

A speedboat increases its speed from 50 ms-1 to 80 ms-1 in a distance of 200 m.
What is the the magnitude of its acceleration?
the time it takes the boat to travel this distance?
i am totally lost on my physics homework..
can some scientist help me out.. and show me the formulas /steps used to solve? thx

2007-11-03 23:50:32 · 3 answers · asked by BoBomakeup 2

Since longitudinal lines are like "markers" for time, (every 15 degrees is one hour) and all longitudinal lines meet at the North Pole and South Pole, what time is it at the exact point that these lines meet?

Or even the North or South pole?


And if you were to stand a meter away from the point of convergence and run around it in a circle, wouldn't that be considered traveling time???

Heheheh...:D

2007-11-03 23:29:47 · 3 answers · asked by 11 4

The electric motor of a model train accelerates the train from rest to 0.580 m/s in 20.0 s. The total mass of the train is 875 g. Find the average power delivered to the train during its acceleration.

i know you use average power=work over change in time, but how to find work?

2007-11-03 23:16:13 · 0 answers · asked by AmandaLiu 1

1. some people used to think that a rocket could not travel to the moon because it would have no air to push aginst once it left the earths atmosphere. we now know that idea was mistaken. what force propels a rocket when it is in a vacuum?

2. since the force that acts on a bullet when a gun is fired is equal and opposite to the force that acts on the gun, does this imply a zero net force and therefore the impossibility of an accleration bullet?

3. suppose you exert 200N on your refrigerator and push it across the kitchen floor at constant velocity. what friction force acts between the refrigerator and the floor? is the friction force equal and opposite to ur 200N push? does the friction force make up the reaction force to your push?

2007-11-03 23:03:52 · 2 answers · asked by Anonymous

1. your weight is the result of the gravitational force of the earth on your body. what is the corresponding reaction force?

2. when a high jumper leaves the ground, what is the source of the upward force that accelerates her? what force acts after her feet are no longer in contact with the ground?

3. If action equals reaction, why isnt the earth pulled into orbvit around ac ommunications satellite?

4. a speeding bus makes contact with a bug that splatters onto the windshield. because of the sudden force, the unfortunate bug undergoes a sudden deceleration. is the corresponding force that the bug exerts against the wind-shield greater, less, or the same? is the resulting deceleration of the bus greater than, less than , or the same as that of bug?

please explain how to do these. thanks!!!!!

2007-11-03 22:57:30 · 1 answers · asked by Anonymous

2007-11-03 22:48:18 · 1 answers · asked by Joel D. 2

fuzziness or movement? sorry if it sounds stupid, its a serious question

2007-11-03 22:24:51 · 4 answers · asked by confused 1

i know its mass*velocity/speed.

but lyk...what's so important about momentum and why do we need to know it?
also, is there an equation for impact?

2007-11-03 22:12:23 · 4 answers · asked by Anonymous

12 balls of equal weight except one are given to u with a balance. find the weight of the differing ball by using the balance scale. you can use the balance scale only for 3 times. You will have to also the ball which is different in weight form others is lighter or heavier. please answer

2007-11-03 21:47:05 · 2 answers · asked by abdul n 1

This is the question:

NASA is giving serious consideration to the concept of solar sailing. A solar sailcraft uses a large,
low mass sail and the energy-momentum of sunlight for propulsion.
(a) Should the sail be absorbing or reflective?
(b) The total power output of the sun is 3.9x1026 W. How large a sail is nececary to propel a
10,000 kg spacecraft against the gravitational force of the sun? Express your result in square
kilometers.
(c) Explain why your answer to part (b) is independent of the distance from the sun?

You will need to use F=GMm/r^2 as the expression for gravitational force.

How to do it!!!

Btw, the answer to (a) is reflective.

2007-11-03 21:36:37 · 1 answers · asked by Anonymous

Heres my rough opinion only based on limited research. As the cable tie snapped, a small amount of torsional movement was created due to vortex shedding and wind eddies. The shedding frequency did not match that of the bridge so it was not the FINAL cause of collapse. However, it did allow some torsional movement. The cross-section of the bridge acted as an airfoil. As it tilted up on the windward side, the velocity of the wind was greater on the top (since a greater distance had to be covered in the same time) than the bottom. This created a greater pressure (P=F/A) on the bottom edge, thus creating a force perpendicular to the cross-section of the bridge. THis motion was repeated until the bridge finally collapsed. As the width to length ratio of the bridge was very small causing the bridge to be too flexable.

2007-11-03 20:26:48 · 4 answers · asked by Anonymous

if you take a spectrum of a star and find that its absorption line of hydrogen which is at 6563A in the lab and is Doppler shifted to 7000A. Is the star moving toward us or away from us? Why?

2007-11-03 19:31:10 · 2 answers · asked by Anonymous

2007-11-03 19:06:16 · 1 answers · asked by AngelOfWar 2

Here's the setup I visualize:

- light emission source;
- chamber that is as close to perfectly reflective (both with regard to light and heat) as possible;
- a tiny outlet hole at the end opposite the light emission source.

It seems that such a thing would produce at least a miniscule amount of thrust, though we lack the materials to make such a chamber. But if we could do it, would it work? Light can push against things and alter their trajectories, so I would assume it has to have -some- thrust capability.

Just curious. :-)

2007-11-03 16:00:18 · 6 answers · asked by uncleclover 5

a bobsled track contains two turns with the radii of 33 m and 24m. Find the centripetal acceleration at each turn for a speed of 34 m/s. Express the answers as multiples of g.( how many times does gravity go into the answer.)

2007-11-03 15:48:08 · 3 answers · asked by ? 2

what happens if you microwave an apple

2007-11-03 15:41:04 · 13 answers · asked by captainpantsbc 2

how much weight do I need pulled by gravity to obtain one horsepower

2007-11-03 15:26:49 · 5 answers · asked by Argeo T 1

In each case, the force vector F and the rod both lie in the plane of the page, the rod has length 4.00m, and the force has magnitude 19.0N.

http://session.masteringphysics.com/problemAsset/1037911/6/YF-10-37.jpg

Which of these options apply to each of these cases?
into the page
out of the page
to the right
upward
the torque is zero

2007-11-03 15:10:02 · 1 answers · asked by Yahoo! Answers Guest Member 1

swimming in the ocean or sitting on the beach?
also, is this related to pruning when you sit in the jacuzzi for long?

2007-11-03 14:43:43 · 2 answers · asked by keyahnoo 2

We have to build an arch bridge for a geometry class, with abutments, voussoirs, and a keystone.

http://www.makingthemodernworld.org.uk/learning_modules/maths/02.TU.03/illustrations/02.IL.24.gif

How big should the measurments of each part be? How many voussoirs should there be?

Would it work if we had 10 voussoirs total? The measurments of each voussoir as:

3 in and 4 in (nonparallel sides)
3 in and 3 in (parallel sides)
75 degrees (bottom base angles)
105 degrees (top base angles)

If that works, what should the keystone measures be? And the abutments?

Thanks so much!

2007-11-03 14:25:11 · 2 answers · asked by Anonymous

i have a physics worksheet but i do not understand the question.

"A ball is kicked such that it moves horizontally at 3 m/s and falls off a 45 m tall cliff."

1.What is the ball's horizontal and vertical acceleration?

i know the vertical acceleration is 9.8 m/s^2 but what about the vertical?

2007-11-03 14:00:51 · 2 answers · asked by Kesha 1

A 2480-Newton bobsled leaves a horizontal track with a speed of 26.9 m/s. It then moves onto a horizontal track lightly sprinkled with sawdust and comes to a stop in a distance of 147 meters. What is the coefficient of kinetic friction between the runners of the sled and the sawdust-covered surface?

2007-11-03 13:32:24 · 1 answers · asked by ags101 2

I am measuring friction and was wondering how the weight of a block affect friction?

2007-11-03 13:28:16 · 4 answers · asked by The Motherload 2

Each rivet has a radius of 4.8 x 10^-3 m and is to be exposed to a shearing stress of no more than 5.1 x 10^8 Pa. What is the maximum tension T that can be applied to each beam, assuming that each rivet carries one-fourth of the total load?

2007-11-03 13:14:55 · 1 answers · asked by Anonymous

A 2.8 kg block is between two horizontal springs. Neither spring is strained when the block is at the position labeled x = 0 m in the drawing. The left spring constant is k(left) = 470 and the right spring constant is k(right) = 660. The block is then displaced a distance of 0.057 m from the position where x = 0 m and is released from rest.

(a) What is the speed of the block when it passes back through the x = 0 m position?

(b) Determine the angular frequency of this system.

http://www.webassign.net/CJ/p10-22.gif

2007-11-03 12:54:06 · 1 answers · asked by Unkown 2

What stays the same when a circuit is driven at its reasonant frequency as compared to when it is driven at any other frequency?
These are the choices:

Impedance, Current, XL, XC,
Linear Frequency, Angular Frequency,
All of These, None of These

2007-11-03 11:21:49 · 3 answers · asked by Anonymous

A coil has a resistance of 48.0 ohms. At a frequency of 80.0 Hz, the voltage across the coil leads the current in it by 52.3 degrees.
Determine the inductance L of the coil.

What formula would I use for this?

2007-11-03 11:18:33 · 1 answers · asked by sahar p 1

I'm doing a reseach on Physics of Lightning and there is way too much information so I'm trying to figure out how I can narrow it down to one specific topic of lightning that still has physics in it. It's college-level also.
Any Help?

2007-11-03 11:10:56 · 2 answers · asked by Anonymous

2. Given f = 255 Hz, what is ω?
________________ [rad s-1]
Answer with Five Sig Figs or N/A if appropriate.

I GOT 1602.2, IS THAT RIGHT???

ALSO:

6. Given ω = 690 [rad s-1], what is the linear frequency?
____________ [Hz]
Use Three Sig figs.

HOW WOULD YOU DO THIS ONE?? PLEASE EXPLAIN, THANKS

2007-11-03 11:10:41 · 1 answers · asked by Anonymous

A 100.0 kg commuter is standing on a train accelerating at 3.70 m/s^2. What coefficient of friction must exist between the commuter's feet and the floor to avoid sliding?

Can anyone help me with this? Can you show me how to solve this, or even what the answer is? Help! Thanks a lot.

2007-11-03 10:35:28 · 1 answers · asked by ☺♠JonasJay♫♦ 5