Physics - March 2007

Two metals, iron and copper, have densities 5.50 x 10^3 kg m^-3 and 8.93 x 10^3 kg m^-3 respectively.
1) estimate the diameter of an atom of copper given that the atomic mass of copper is 63.5
2) do as 1) for iron with Ar=56
3) Find the estimation of the ratio of their spherical volumes.
4) Explain whether or not your estimations in 1) and 2) is greater or less than the accepted values.
5) Do their crystalline structures matter for finding the ratio? Give reason/s...

2007-03-29 17:09:22 · 2 answers · asked by Warm Ice 1

Seem Canada is using heavy water reactor and the US is using light water. what is the different between them in the following area?

1. construction cost
2. running cost
3. maturity of the technology
4. safety
5. effiecncy
6. any other...

2007-03-29 16:28:16 · 2 answers · asked by tak in hong kong 1

2007-03-29 16:25:19 · 3 answers · asked by Anonymous

2007-03-29 16:14:57 · 9 answers · asked by Anonymous

Which is more dangerous? Current or Voltage?

What determines how much current is flowing through you?

Can someone give me 3 examples, or three things that determine it?

Thanks!

2007-03-29 15:02:28 · 10 answers · asked by xItsMeJenniferx 1

Gaetan Boucher started from rest and skated around a circular ice track of radius 100m. He maintained a constant rate of increase of his speed and finished one complete lap in 30s. Calculate the magnitude of his total acceleration as he passed a point 1/4 of the distance around thet rack from the start.

THANK YOU.

2007-03-29 14:58:47 · 1 answers · asked by Thrish 1

An object starts at time t = 0 with a velocity of v0 = +50 m/s and undergoes a constant acceleration of a = -11 m/s2.

I've already figured out a and b but I need help with c,d and e.

a)At what time does the speed of the object reach zero?
answer=4.56

b) How far from its starting (t = 0) position is the object at time t1?
answer=113.6

c) At what time does the object again pass through the starting (t = 0) position?

t2=____?___

d) If the object had initially been moving twice as fast (100 m/s), how far would it have gone before its velocity reached zero?
D=______?____

e) Suppose a second object begins moving with a constant speed of v = 50 m/s in the same direction from the same location at the same time as the object in part (d). At what time do the paths of these two objects once again cross?

tmeet= _____?____

2007-03-29 14:54:30 · 2 answers · asked by fabulous101 2

2007-03-29 14:43:52 · 2 answers · asked by Anonymous

A 4.86 kb ball traveling at 3.15 m/s collides with a 5.09 kg ball moving at 1.22 m/s in the same direction as the first ball. The collision is elastic.

a) Find the final velocity, magnitude + direction of each ball
b) Calculate how much energy was transfered during the collision and identify which ball gained and lost the energy.
c) Calculate the magnitude of the impulse that each ball experiences.

I think I got part a: I put 1.17 and 3.10.
I think part b is -9.57 and 9.62

But part b I didn't know how to do.

Thanks!

2007-03-29 14:16:13 · 1 answers · asked by truthiness89 2

initial position=10m, velocity= -1.0m/s accleration= 0.1

2007-03-29 13:55:05 · 1 answers · asked by Anonymous

A neutron collides elastically with a helium nucleus (at rest initially) whose mass is four times that of the neutron. The helium nucleus is observed to rebound at an angle '2 = 45° from the neutron's initial direction. The neutron's initial speed is 6.2 105 m/s. Determine the angle at which the neutron rebounds, '1, measured from its initial direction.

Angle?

Speed of Neutron after collision-

speed of helium nucleus after collision-

Thank you

2007-03-29 13:51:01 · 1 answers · asked by Anonymous

Write the first and second laws of probability

2007-03-29 13:49:41 · 0 answers · asked by Anonymous

2007-03-29 13:15:01 · 2 answers · asked by Anonymous

2007-03-29 12:59:08 · 4 answers · asked by tinkerbella 5

Given the Otis locking mechanism which I assume is standard worlwide

2007-03-29 12:56:01 · 5 answers · asked by coomraider 1

A $20 bill is 6.1 in. by 2.6 in. Calculate the magnitude of the force that the printing press applies to one side of the bill.


I have no idea even how to start this problem...

2007-03-29 12:55:34 · 3 answers · asked by ..*Real-ality*.. 3

An alloy that is one karat gold contains a weight of pure gold that is one part in twenty-four. What is the volume of gold in a 18.0 karat gold necklace whose weight is 1.24 N?


I have no idea even how to start this problem. I tried doing a % and i was WAY off...

2007-03-29 12:50:09 · 4 answers · asked by ..*Real-ality*.. 3

2007-03-29 12:48:43 · 2 answers · asked by Anonymous

Would you be unhurt?

2007-03-29 12:40:54 · 12 answers · asked by coomraider 1

2007-03-29 12:24:01 · 3 answers · asked by havok45 1

I really do hate it, but I feel I should know it. Maybe my hatred of it is due to my fear of it...
Thanks!

2007-03-29 12:15:18 · 8 answers · asked by Anonymous

If dry ice melted could I walk on it without getting wet?

2007-03-29 11:58:28 · 5 answers · asked by pirate_princess_1 1

is it theoredicly possible to time travel or is it just a hollywood myth?Please give the reasons why it is or why its not..thanks in advance

2007-03-29 11:41:10 · 5 answers · asked by Anonymous

I am planning to try an connect a homemade electromagnet to an AC adaptor. I have 1 that delivers 9-volts and 300milli-amps and 1 that delivers 6-volts and 2.2 amps. Which one should I use to make the magnet as powerful as possible?

2007-03-29 11:28:47 · 9 answers · asked by Anonymous

i just figure thiers billions and billions of galixy's out thier, so everything should be possible right.

2007-03-29 10:31:50 · 6 answers · asked by SHELLTOE BISCUITS 3

my friend told me that if i got a glass of saltwater and clamped a wire with like.. aligator type teeth to two chopsticks and attatched it to a light bulb stand with a light bulb in it, if i moved the chipsticks farther and closer to eachother it would make the light bulb become brighter and less bright.
is this true? what can i use? i want to demonstrate electricity for a science project and i want to show how different types of electricity can increase and decrease in power.

2007-03-29 10:30:19 · 4 answers · asked by aliwali 2

A cylinder with moment of inertia I1 rotates with angular velocity 0 about a frictionless vertical axle. A second cylinder, with moment of inertia I2, initially not rotating, drops onto the first cylinder (Fig. P8.55). Because the surfaces are rough, the two eventually reach the same angular velocity, .

(a) Calculate . (Use I1 for I1, I2 for I2, and w0 for 0 in your equation.)

(b) Show that energy is lost in this situation (Do this on paper. Your instructor may ask you to turn in this work.), and calculate the ratio of the final to the initial kinetic energy. (Use I1 for I1, I2 for I2, w for , and w0 for 0 in your equation.)
http://www.webassign.net/sercp/p8-55.gif

2007-03-29 10:25:51 · 2 answers · asked by Emma 1

At a playground, an 15 kg child plays on a slide that drops through a height of 2.4 m. The child starts at rest at the top of the slide. On the way down, the slide does a nonconservative work of -211.7 J on the child. What is the child's speed at the bottom the slide? this is an energy problem by the way.

2007-03-29 10:07:19 · 1 answers · asked by soccerjock 2

Catching a wave, a 83 kg surfer starts with a speed of 1.3 m/s, drops through a height of 2.05 m, and ends with a speed of 8.2 m/s. How much nonconservative work was done on the surfer?
J

2007-03-29 10:04:50 · 1 answers · asked by soccerjock 2

At a local playground, a child on a swing has a speed of 3.4 m/s when the swing is at its lowest point.

a.) To what maximum vertical height (above the bottom of the swing) does the child rise, assuming he sits still and "coasts"?
m

b.) Reanswer part a, with the initial speed of the child being half as much.
m

c.) During this process, how much work is done by the tension in the rope? (What assumptions did you make in part a?)
J

2007-03-29 10:03:22 · 2 answers · asked by soccerjock 2