Physics - December 2007

2007-12-18 18:39:12 · 1 answers · asked by Sandeep P 1

2007-12-18 18:36:19 · 12 answers · asked by Anonymous

Does anyone know what's the 2nd law of motion for basketball?

I know it's Force divided by mass...

2007-12-18 17:43:22 · 5 answers · asked by Mr.Impossible 4

m1v1+m2v2 = (m1+m2)v3

I know that it has something to do with the conservation of momentum, but I'm not sure exactly what.
I know this one:
m1v1i+m2v2i+=m1v1f+m2v2f

But what's that first one?

Thanks!

2007-12-18 16:51:42 · 2 answers · asked by mew1033 2

A lizard lies in the sun to regulate its body temperture. Which form of heat transfer allows the sun to warm the lizard?
a. conduction
b. convection
c. radiation
d. no heat will transfer takes place

What happens when you put in your drink to cool it down?
a. The ice transfers coldness to the warmer drink
b. Heat is transfers from the ice to the drink
c. heat is transferred from the drink to the ice.
d. the ice cracks and releases cold air into the drink

no mean answer PLZ and please explain how you got the answer

2007-12-18 16:50:31 · 2 answers · asked by VATO200 1

A small block of mass 2m initially rests on a track at the bottom of the circular, vertical loop-the-loop, which as radius = r. The surface contact between the block and the loop is frictionless. A bullet of mass m strikes the block horizontally with initial velocity v and remains embedded in the block as the block and bullet circle the loop. Determine each in terms of m, v, r, and g

a. the speed of the block and bullet immediately after impact
b. the kinetic energy of the block and bullet when they reach a point on the loop-the-loop (stays on the track), which is half the height of the loop-the-loop. The height at this point = r.
c. the minimum initial speed of the bullet if the block and bullet are to successfully execute a complete circuit of the loop.

2007-12-18 16:45:53 · 1 answers · asked by M4tr!x 2

Karen has a mass of 57.0kg and she rides up the escalator. Karen rode a distance of 65m. How much work did the escalator do on Karen if it has an inclination of 30 degrees?

The answer is 1.8 x 10^4 Joules. But I don't know how to arrive at it.

2007-12-18 16:44:02 · 1 answers · asked by david 2

Which form of matter is usually the best conductor of heat?
a. solid
b. liquid
c. gas
d. plasma

A juggler is juggling four beanbags. When does each beanbag have the greatest potential energy with respect to the floor?
a. just after it is thrown
b. just before it is caught
c. when it reaches its highest point
d. when it is moving at its greatest speed

Heat is transferred from the sun to Earth-
a. conduction
b. convection
c. fusion
d. radiation

2007-12-18 16:38:58 · 2 answers · asked by VATO200 1

On the planet, a man is flying toward his mate at 25 m/s while singing at a frequency of 1200Hz. If the stationary female hears a tone of 1240Hz, what is the speed of sound in the atmosphere?

2007-12-18 16:17:16 · 1 answers · asked by Anonymous

Find the fundamental frequency and the frequency of the first three overtones of a pipe 45 cm long

a) if the pipe is open at both ends
b) if the pipe is closed at one end. Use v=344m/s
c) For each of the above cases, what is the number of the highest harmonic that may be heard by a person who can hear frequencies from 20Hz to 20,000 Hz

2007-12-18 16:11:01 · 1 answers · asked by Anonymous

2007-12-18 15:40:16 · 2 answers · asked by Anonymous

42. A liquid (p = 1.65 g/cm^3) flows through two horizontal sections of tubing joined end to end. In the first section the
cross-sectional area is 10.0 cm^2, the flow speed is 275 cm/ s. and the pressure is 1.20 * 10^5 Pa. In the second section
the cross-sectional area is 2.50 cm^2. Calculate the smaller section's (a) flow speed and (b) pressure.

43. A hypodermic syringe contains a medicine with the den-SM sity of water. The barrel of the svringe has a cross-sectional
area of 2.50 X 1O^-5 m^2. In the absence of a force on the plunger, the pressure everywhere is 1.00 atm. A force F of
magnitude 2.00 N is exerted on the plunger, making medicine squirt from the needle. Determine the medicine's flow speed
through the needle. Assume that the pressure in the needle remains equal to 1.00 atm and that the syringe is horizontal.

44. When a person inhales, air moves down the bronchus (windpipe) at 15 cm/s. The average flow speed of the air
doubles through a constriction in the bronchus. Assuming incompressible flow, determine the pressure drop in the
constriction.

2007-12-18 15:30:47 · 1 answers · asked by Jonny C 2

A 45 kg girl is standing on a 150 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.5 m/s to the right relative to the plank.

A) what is her velocity relative to the surface of the ice?
B) What is the velocity of the plank relative to the surface of the ice?

I'm confused. I'm pretty sure I'm doing it right, yet I'm getting the wrong answer.
Here's what I'm doing:

M(girl)=45kg
M(plank)=150kg
V(girl)[initial]=0
V(plank)[initial]=0
V(girl)[final]=1.5
V(plank)[final]=?

M(girl)V(girl)[initial] + M(plank)V(plank)[initial] = M(girl)V(girl)[final] + M(plank)V(plank)[final]

So: 0 + 0 = (45)(1.50) + (150)(V)
So: 0 = 67.5 + 150(V)
So: 67.5 = -150(V)
So: V = -.45 <- Final Plank velocity.

So if the girl is moving 1.50 m/s, and the plank is moving -.45 m/s. Wouldn't her velocity relative to the ice be 1.50 - .45 = 1.05?

Book answers:
a) 1.15 m/s
b) -0.346 m/s

2007-12-18 13:58:52 · 2 answers · asked by mew1033 2

Ok help me out with these questions. These are due tomorrow with a bunch of other ones so i need all the help i can get. Thanks

1.Why is the constant temperature of boiling water on a hot stove evidence that boiling is a cooling process?

2.Will potatoes boiling in a pot of water cook faster if the water is boiling vigorously than if the water is boiling gently?

3. People who live where snowfall is common will attest to the fact thats air tempuratures are always higher on snowy days than on clear days. Some people get cause and effect mixed up when they say that snowfall cannot occur on very cold days. Explain.

4. On cold winter days the windows of your warm home sometimes get wet on the inside. Why is this so?

2007-12-18 13:55:01 · 3 answers · asked by varsitygurl 1

Why won't it ignite?

2007-12-18 13:47:56 · 1 answers · asked by Anonymous

I have to create a vehicle that is propelled by Newton's 3rd Law. "For every action, there is an equal and opposite reaction." Basically, something that makes the car go by being pushed against the wall. I've been thinking like a spring or something, but i think everyone's going to do that. Any ideas?

2007-12-18 13:17:31 · 6 answers · asked by Anonymous

A 65.0 kg diver steps off a diving board and drops straight down into the water. The net force when in the water is an upward 1250 N. If the diver comes to rest 4.0 m below the water's surface, what is the total distance between the diving board and the diver's stopping point underwater?

2007-12-18 13:17:03 · 1 answers · asked by Anonymous

2007-12-18 13:09:28 · 1 answers · asked by Anonymous

I have to do an egg drop for Physics which I made and tested my design off a 3 story building. I made a cone and lid out off poster board and stuffed the inside with a bag of cotton balls and the egg in the middle(which survived). Now I have to explain why my egg survived and i don't know why because the only things I can think of is air resistance, elastic potential energy, and velocity, which none of the design uses. Can anyone tell me why it survived using physics?

2007-12-18 12:48:29 · 4 answers · asked by KiMkIm 2

"A 10m wire is hung from a high ceiling and held tightly below by a large mass. Standing waves are created in the wire by air currents that mass over the wire, setting it in motion. If the speed of the standing wave is 335 m/s and its frequency is 67 Hz, what is its wavelength?"
I know Wavelength= Velocity divided by Frequency, but the 10m wire is messing me up. Is that unneeded information to throw me off, or how do I put it into the equation to get a correct answer. I am thinking it is 335/67, but I'm not sure, and this is for a quiz grade.
If you could explain how to do it, that would be lovely. :]
Thanks

2007-12-18 12:19:03 · 1 answers · asked by Anonymous

whats the difference ?
name atleast five or as many as you can think of :]

state your source

2007-12-18 12:16:55 · 4 answers · asked by Anonymous

I know that there are pretty simple ways to solve these problems (there always are with these type of assignments) but I really can't figure them out. I have the following image: http://www.eggloaf.com/coaster.PNG
And I am supposed to calculate the minimum value of h such that the cart can stay on the top of the loop without falling off of the track (friction is negligible). I've tried just about every formula I can think of, but I can't come up with a numeric answer...
Also, it asks to calculate the normal force as a function of theta from 0 to 180 degrees, where theta is the angle formed between the bottom of the loop and the position of the cart. I don't even know where to begin with this one...

Honestly, any help at all would be really appreciated.

2007-12-18 12:05:49 · 3 answers · asked by Beeflog 1

After a canon ball is fired into fricionless space, the amount of force needed to keep it going equals.

A) twice the force with which it was fired.
B) the same amount of force with which it was fired.
C) one half the force with which it was fired.
D) zero, since no force is necessary to keep it moving.

2007-12-18 11:31:44 · 3 answers · asked by Anonymous

A high speed proton has kenetic energy of 898 MeV. What is its speed? (the rest energy of a proton is 939 MeV) The answer is .859c but i am not sure how to solve it.

2007-12-18 11:22:32 · 1 answers · asked by mastersource2005 5

Which has more mass a Kg of feathers or a Kg of iron?

2007-12-18 11:08:22 · 6 answers · asked by blondie199077 2

2007-12-18 10:36:48 · 3 answers · asked by Alexander 6

A 5 kilogram wooden block, is placed on an adjustable wooden inclined plane.
a.) What is the angle of inclination above which the block will start to slide down the plane.
b.) At what angle of inclined will the block then slide down the plane at a constant speed.

Thanks

2007-12-18 10:25:51 · 2 answers · asked by ♥♫♪ The Cool one ♥♫♪ 2

A child and sled with a combined mass of 48.6 kg slide down a frictionless hill that is 8.02 m high. If the sled starts from rest, what is its speed at the bottom of the hill?

and

A person doing a chin-up weighs 755 N, disregarding the weight of the arms. During the first 25.0 cm of the lift, each arm exerts an upward force of 381 N on the torso. If the upward movement starts from rest, what is the person's speed at this point?

2007-12-18 10:24:42 · 1 answers · asked by Anonymous

please help answer any of the 3 quesitons thank you

1. A 2.38 kg mass with an initial velocity of
v
1 = aˆı, where a = 3.67 m/s collides with
and sticks to a 2.89 kg mass with an initial
velocity of v1 = bˆj, where b = −4.8 m/s.
Find the final speed of the composite mass.
Answer in units of m/s.

2. Three point mass particles are located in a
plane:
4.25 kg located at the origin,
7.2675 kg at [(6.24 cm), (12.48 cm)],
and 3.02175 kg at [(18.6576 cm), (0 cm)].
How far is the center of mass of the three
particles from the origin? Answer in units of
cm.

3. A(n) 17 kg ob ject, initially at rest in free
space, “explodes” into three segments. The
masses of two of these segments are both 6 kg
and their velocities are 6.3 m/s. The an-
gle between the direction of motion of these
segments is 46 degrees.
What is the speed of the third segment?
Answer in units of m/s.


PLEASE SHOW WORK SO I CAN LEARN IT

THANK YOU

2007-12-18 10:23:05 · 1 answers · asked by mimi j 1

A 65.0 kg diver steps off a diving board and drops straight down into the water. The net force when in the water is an upward 1250 N. If the diver comes to rest 4.0 m below the water's surface, what is the total distance between the diving board and the diver's stopping point underwater?

2007-12-18 10:21:04 · 1 answers · asked by Anonymous