Physics - April 2007

hi i am wondering what the reaction forces are to

gravity
and the force of a balloon pushing air backwards

for the balloon will it be the force of propulsion?
any help much appreciated, thanks :)

2007-04-19 05:29:35 · 4 answers · asked by GB 2

Nuclear power generation has been very controversial. Cite the advantages of using nuclear power plants. Research the use of nuclear power for electricity production in the rest of the worl. Compare this to the situation in the USA. Based on what you learn in your research, predict whether nuclear power will made a "comeback" in the USA.

2007-04-19 05:24:42 · 3 answers · asked by Anonymous

A sled and a rider with a combined mass of 60·kg are at the top of a hill, 10·m above ground level. The sled is given a push, providing an initial KE (for the sled and rider) of 1700·J at the top of the hill. Use g=10·m/s2.
(a) Choosing a reference level at the bottom of the hill, what is the PE of the sled and rider at the top of the hill? J.

(b) After the push, what is the total mechanical energy of the sled and rider at the top of the hill? J.

(c) If friction and air resistance can be ignored, what will be the KE of the sled and rider at the bottom of the hill? J.

(d) Compared to your answer for the previous part, how much KE would the sled and rider have if friction and air resistance cannot be ignored? Choose one answer only.
same KE
more KE
less KE
KE could be more, less, or the same

2007-04-19 05:23:12 · 1 answers · asked by John 2

Allowing for a coal-fired plant's efficiency and for losses in the power lines, approx. 1.1 kg of CO(sub. 2) is produced for KWH of electricity delivered to your home. Calculate the mass and volume of CO(sub. 2) produced to run the light bulb.

I pound CO(sub. 2)= 250 L

Light bulb is 100 watt burning for 7 hours a day and 365 days a year.

2007-04-19 05:21:48 · 2 answers · asked by Anonymous

2 things:

1. How can I determine the wavelength of a particular light falling on my LDR?

2. How can I measure the intensity of the light falling on my LDR?

My prior investigations were RUBBISH, so any help appreciated, answers on a postcard please! (Or in the boxes below).

2007-04-19 05:17:35 · 5 answers · asked by Anonymous

I want to check some lamps by testing their outpu at different wavelengths, and I HAVE to use an LDR in my experiment. Also, how does the intensity of light vary with wavelength?

2007-04-19 04:45:27 · 4 answers · asked by Anonymous

Well, you know the drill

Two small balls separated horizontally by distance d = 1cm
dropped into the hole.

What is horizonatal separation between the balls when they
reemerge 85 minutes later after one full period of oscillation?

The answer is almost as cool as Euler's formula, please
keep it in closed form.

2007-04-19 04:14:45 · 18 answers · asked by Alexander 6

Does it have anything to do with spinning?

2007-04-19 04:08:37 · 18 answers · asked by AaronX 2

s = 10 + 5t +12t^2 - t^3

Find (i) the time when it's speed is zero
(showing wrkings pls)

Find (ii) the velocity when the acceleration is zero

2) The period of oscillation of a simple pendulum is given by T= 2pi sqrt (L/g) where L is the length of the pendulum and g is the acceleration due to gravity (as constant g = 9.8 m/s^2).

Find the approximate percentage change in T if L is increased by 5%.
(Pls show workings step by step)
Thanks

2007-04-19 03:56:25 · 1 answers · asked by SHIBZ 2

My partner and I are working on a physics project which deals with Ac and we need to explain how they are related. Can you help best answer get 10 points.

2007-04-19 03:44:33 · 5 answers · asked by Mz.Thang 3

Will you land back at the same point?

What if the train has both its ends open?

2007-04-19 03:27:38 · 8 answers · asked by ```Lion~~~ 2

Specific heat capacity of chalk= 3543 J * kg/K
molar heat capacity of chalk = 105.6 J * moles/K
Specific heat capacity of big metal ball = 356.8 J * kg/K
molar heat capacity of big metal ball = 110.6 J * moles/K
Specific heat capacity of marble= 4435 J * kg/K
molar heat capacity of marble = 68.8 J * moles/K

2007-04-19 03:26:28 · 3 answers · asked by Anonymous

I just can't find any info on this. I think it might have something to do with taking the heboglobins out of our blood.

2007-04-19 02:49:43 · 2 answers · asked by rjnutterbutter 2

The universe at a subatomic has a basic symetry to it (e.g electrons and protons) with equal amounts of each opposite particle (e.g quarks) so why doesn't this apply to matter and antimatter?

Why don't they exist in equal amounts in order to maintain cosmic balance?

If they do exist in equal amounts why didn't they just annihilate each other at the begining of the universe when they were in relatively close proximity?

2007-04-19 02:49:22 · 6 answers · asked by Anonymous

Will the ant die? Or will air friction save it?

2007-04-19 02:15:01 · 8 answers · asked by joshbax_88 2

Peace!

2007-04-19 01:56:16 · 6 answers · asked by Emerald 2

My U.S. history teacher told me this last year. That we can't see light bulbs 'blink' about 30 times per sec because our eyes aren't fast enough to see that. I think that's bs, but did anyone ever heard of this?

2007-04-19 01:50:35 · 11 answers · asked by Anonymous

In short, why is Venus the only planet in our solar system to rotate clockwise?

Please thank you.

2007-04-19 01:44:05 · 5 answers · asked by John d 1

2007-04-19 00:38:14 · 25 answers · asked by Anonymous

how do electrons moving through a wire create a magnetic field?

2007-04-18 23:57:59 · 5 answers · asked by rob f 1

2007-04-18 23:41:59 · 4 answers · asked by salman 1

what is the impact that it had in the evolution of modern physics, as well as, on our everyday life (the social, economical and, possible, political impact).

2007-04-18 22:01:45 · 3 answers · asked by pop 2

with equal speeds relative to earth. As measured by a passenger in one of the spaceships, the other spaceship is 96 m long. What is the speed of the spaceships?

a) c/7
b) c/5
c)c/3
d)c/4

2007-04-18 21:08:16 · 2 answers · asked by alain3022 1

a) 0.984c
b) 0.950c
c) 0.968c
d) 0.976c

2007-04-18 21:05:21 · 2 answers · asked by alain3022 1

A) 2.01 X 10 ^15 Hz
b) 3.01 x 10^15 Hz
c) 1.50 x 10^15 Hz
d) 5.02 x 10^15 Hz

2007-04-18 20:46:41 · 2 answers · asked by Anonymous

cause photoelectron emission from this metal?

a) 653 nm
b) 14.0 nm
c) 344 nm
d) 231 nm

2007-04-18 20:42:09 · 1 answers · asked by Anonymous

Brian is holding a pencil at an angle of 30.0 degrees with the direction of travel, as seen by brian. What angle does the pencil make with the direction of travel, as seen in the frame of reference of the observer?

a) 30 degrees
b) 29 degrees
c) 31 degrees
d) 32 degrees

2007-04-18 20:38:21 · 2 answers · asked by Anonymous

between its creation in a nuclear process and its extinction into decay products, as measured in a frame of reference at rest with respect to the pion. An average pion is traveling at 0.270c relative to earth. How far does it travel in its lifetime, relative to earth?

a) 3.22 m
b) 2.23 m
c) 2.15 m
d) 2.07 m

2007-04-18 20:22:14 · 2 answers · asked by mailyn215 1

2007-04-18 20:19:59 · 2 answers · asked by rungano 1

over a smooth pulley .Both object start from rest . find the maximum height by the 2.0kg object

2007-04-18 18:06:26 · 2 answers · asked by vInE r 1