Physics - September 2007

Evolution seems to defy all logic, how can, in such a hostile environment, something good come out of something so destructive? And then against all odds, keep getting better and better? And if it took thousands of failed tries for something to change even more for the better, doesn't it seem odd that suddenly, it worked perfectly?
Especially when the 2nd law of thermodynamic states that given time, only increased disorder will result.

2007-09-16 06:07:47 · 9 answers · asked by Anonymous

2007-09-16 05:40:21 · 1 answers · asked by AFA 1

A relief airplane is delivering a food package to a group of people stranded on a very small island. The island is too small for the plane to land on, and the only way to deliver the package is by dropping it. The airplane flies horizontally with constant speed of 290 mph at an altitude of 600m . The positive x and y directions are defined in the figure. For all parts, assume that the "island" refers to the point at a distance from the point at which the package is released, as shown in the figure. Ignore the height of this point above sea level. Assume that the acceleration due to gravity is = 9.80m/s^2 .After a package is ejected from the plane, how long will it take for it to reach sea level from the time it is ejected? Assume that the package, like the plane, has an initial velocity of 290 in the horizontal direction.If the package is to land right on the island, at what horizontal distance from the plane to the island should the package be released?
What is the speed of the Pg

2007-09-16 05:09:28 · 3 answers · asked by Frostie K 1

2007-09-16 04:47:00 · 3 answers · asked by Tony K 1

A car (mass of 1700 kg) is parked on a road that rises 15 degrees above the horizontal. What are the magnitudes of (a) the normal force and (b) the frictional force that ground exerts on the tires?
(1.0 is the coeffeciant of static friction and 0.8 is the coefficent of kinetic friction between concrete and rubber)
ok now what????????????

2007-09-16 04:40:35 · 6 answers · asked by kwali 2

An interesting phenomenon around here... LOTS of people answering relativity questions referring to the increase of mass as speed approaches c.

This is an obsolete interpretation. In modern physics literature, the word "mass" always refers to rest mass. The variable M always refers to mass, which always refers to rest mass.

It's obsolete for very good reasons: you can't correctly calculate effects of gravity using "relativistic mass;" relativistic mass is not invarient, but rest mass is. Even if you're using it to illustrate changes of inertia, it's different in different directions: you'd have to give a particle a different mass for each of x,y, and z motions. Scalar, invarient mass becomes a noninvarient vector. Messy.

When you explain that bodies cannot travel at c by explaining that they get more and more massive, it easily misleads the asker into thinking that if they were to travel at c they would become fatter and fatter in their own reference frame, which is clearly untrue.

2007-09-16 04:23:21 · 2 answers · asked by ZikZak 6

2007-09-16 04:14:30 · 2 answers · asked by Sourkrout 3

You are working as a consultant on a video game designing a bomb site for a World War I airplane. In this game, the plane you are flying is traveling horizontally at 44.8 m/s at an altitude of 130 m when it drops a bomb.

(a) Determine how far horizontally from the target you should release the bomb.
(b) What direction is the bomb moving just before it hits the target?

This is the question I'm having trouble with. It shouldn't be that hard, but it's just not clicking for some reason. I don't necessarily want someone to do the problem (that's my job) but tell me how I should go about solving it. Thanks.

2007-09-16 04:00:56 · 4 answers · asked by Doogin 3

2007-09-16 03:47:42 · 5 answers · asked by Valeree B 2

2007-09-16 03:26:26 · 16 answers · asked by Neill 3

2007-09-16 03:22:06 · 2 answers · asked by Anonymous

why heating element of a kettle always found at the bottom

2007-09-16 03:16:45 · 4 answers · asked by ™ 3

Consider a air-tight box which has insects(100000 of them) inside it. The box without insects weigh 100 kgs. (say). The box considered i.e the box with insects inside it weigh 200 kgs.(say). Now, if all the insects inside the box starts flying, does the weight of the box (i.e. 200 kgs) change?
Note: Consider that the box is weighed after a considerable amount of time with the insects flying inside the box.

2007-09-16 02:47:54 · 1 answers · asked by Swarup 1

Two basketball players are essentially equal in all respects. (They are the same height, they jump with the same initial velocity, etc.) In particular, by jumping they can raise their centers of mass the same vertical distance, (called H their "vertical leap"). The first player, Arabella, wishes to shoot over the second player, Boris, and for this she needs to be as high above Boris as possible. Arabella jumps at time , and Boris jumps later, at time (his reaction time). Assume that Arabella has not yet reached her maximum height when Boris jumps.



1)Find the vertical displacement , D(t) = H(a)(t) - H(b)(t) as a function of time for the interval 0 < t < t(r) , where H(a)(t) is the height of the raised hands of Arabella, while H(b)(t) is the height of the raised hands of Boris.
Express the vertical displacement in terms of H, g , and t.

2007-09-16 02:37:32 · 2 answers · asked by Gills 1

i found out that:

x(man)t(catch)=x(bus)t(catch)

and

-b+ct(catch)=(1/2)at^2(catch)

A man is running at speed c (much less than the speed of light) to catch a bus already at a stop. At t=0 , when he is a distance b from the door to the bus, the bus starts moving with the positive acceleration a .
Use a coordinate system with x=0 at the door of the stopped bus.

So,

What is the minimum value of c for which the man will catch the bus?

Express the minimum value for the man's speed in terms of a and b ?

PLEASE clear explanations...thanks

2007-09-16 02:25:09 · 2 answers · asked by Tommy 2

2007-09-16 01:38:39 · 10 answers · asked by moose_uncanny 2

Describe an expirement you could counduct to determine the mass of a half metre ruler using the principle of moments.

Also state materials/ equipments used, result to be taken and how you would use these results to arrive at the mass of the ruler.

2007-09-16 00:34:08 · 2 answers · asked by Candy 1

A ball is thrown vertically at 20ms^-1 from the surface of the Earth. With what speed would it have to be thrown on Jupiter, where g is = 22.5ms^-2, in order to reach the same height?

2007-09-16 00:29:48 · 3 answers · asked by ur having a right laugh innit 2

A stone is projected vertically upward at an initial speed of 60ms^-1. Caculate

a) The maximum height reached
b) The time of flight
c) its speed when 100m high

2007-09-16 00:16:07 · 1 answers · asked by ur having a right laugh innit 2

Does anyone know? Thanks

2007-09-15 22:52:01 · 11 answers · asked by Kit 2

2007-09-15 21:19:35 · 1 answers · asked by gini 1

A portable CD player uses a current of 6.8 mA at a potential difference of 3 V. (a) How much energy does the player use in 41 minutes? (b) Suppose the player has a mass of 0.65 kg. How many minutes should the player operate on so that the energy can lift the CD player through a height of 1m?
(a) Energy consumed in 41 minutes is J.
(b) The time for the CD player is minutes.

I am extremely bad with physics so along with an explanation, and answer would be much appreciated! Thanks!

2007-09-15 21:10:03 · 2 answers · asked by Anonymous

The resistor in an RC circuit has a resistance of 181 Ω. (a) What is the capacitance must be used in this circuit so that the time constant is 2 ms? (b) Using the capacitance determined by (a) calculate the current in the circuit 4 ms after the switch is closed. Assuming that the capacitor is uncharged initially and the EMF of the battery is 9.0 V.
(a) The capacitance is ? µF.
(b) The current in the circuit is ? mA.


Im extremely bad with physics so along with an explanation, an answer would be much appreciated! Thanks!

2007-09-15 21:08:34 · 2 answers · asked by Anonymous

The picture tube in a particular television draws a current of 13 A. How many electrons strike the viewing screen every second?
?electrons/s

2007-09-15 21:03:15 · 2 answers · asked by Anonymous

I have a friend who is an astrophysist at a major university and he has presented what are two opinions in the science community. One being it is and will be within the next two generations, the other being likely never. I would like to hear some other opinions from other physists and methematicians just out of curiousity.

2007-09-15 20:41:24 · 2 answers · asked by steve s 2

How is the kinetic energy formula derived? From where does it derive?

2007-09-15 20:36:22 · 3 answers · asked by mehrdad_baghery 2

2007-09-15 20:23:46 · 2 answers · asked by Duna 2

of a car is left running, and the car is not moving. The engine is on and thats it. Nobody's in the car, only the engine is left running. So my question to you is, how long does it take for the fuel to go from full to empty??? Example: 1 day, 1 week, 1 month.... I don't know you tell me. how long???

I'd really appreciate it if you can tell me how long will it take for the engine to stop running (going from full to empty).

The car is a 2007 Chevrolet Aveo, 1.6 litter L4 Engine, fuel injection automatic 4 speed transmission. EPA estimated MPG 26 city, 34 highway.

Click this link for more info about the car:
http://www.chevrolet.com/aveo/specificat...

2007-09-15 19:26:27 · 3 answers · asked by Anonymous

2007-09-15 19:06:27 · 4 answers · asked by j c 1

IN terms of viscosity??????

2007-09-15 18:57:43 · 1 answers · asked by Duna 2