Physics - March 2007

in front of my assistant with my back facing the direction of travel (me looking at assistant who is facing me) and I turned on a flashlight pointed at him/her would he/she:

A. See no light at all
B. See a bright flash as the light passes them by
C. See a contiuously lit flash light
D. Wish they'd brought some Valium

If possible, please explain your answer. Thanks!

2007-03-22 08:58:59 · 11 answers · asked by krodgibami 5

What is the wavelength range reflected by a regular mirror, and please state your source.

2007-03-22 08:55:58 · 1 answers · asked by Anonymous

Assuming that the conditions are the same, wind velocity and direction, currents, motion of the waves, etc.

2007-03-22 08:52:41 · 5 answers · asked by Lost. at. Sea. 7

SITUATION: A 1300-kg car travels at 22 m/s and then quickly stops in 3.6 s to avoid an obstacle.

QUESTIONS:
a) What is the initial speed of the car in mph?
b) What is the initial kinetic energy of the car in kilojoules (kJ)?
c) What is the initial momentum of the car? (In kg*m/s)
d) What is the magnitude of the impulse necessary to stop the car? (in kg*m/s)
e) What is the magnitude of the average force in kiloNewtons (kN) that stopped the car?
f) What is the magnitude of the average acceleration that stopped the car? (m/s^2)


thanks..

2007-03-22 08:48:05 · 3 answers · asked by Anonymous

I am on a train with only 1 carrige 500 metres long,the train is travelling at twice the speed of sound and can go on for another few hours at this speed in a straight line.
i am at the front of the train and another person with a gun is standing at the back of the train, there is nothing else in the carrage apart from me and the other person,he shoots at me , the bullet is travelling at the speed of sound,
would the bullet hit me?

2007-03-22 08:38:28 · 21 answers · asked by spamalot 1

red tacton technology uses human area network.

2007-03-22 08:24:02 · 2 answers · asked by pradeep mca 1

After a coin was accidently dropped on the floor, it is rolling around the circle R = 0.4m. The speed of the coin v = 1.00 m/s. What is the inclination angle of the coin to the vertical?

The coin is a thin uniform disk of radius r << R.
The force of friction is sufficient to keep the coin from slipping.
Ignore all enrgy losses, air, etc..

2007-03-22 08:21:03 · 3 answers · asked by Alexander 6

Not homework and No Sermons Please.

2007-03-22 08:13:45 · 2 answers · asked by Dovey 7

A drop of liquid falls on a student’s skin and quickly evaporates.
What is the effect on the skin and the reason?
A The skin cools because the most energetic molecules escape from the liquid.
B The skin cools because the most energetic molecules remain in the liquid.
C The skin warms because the most energetic molecules escape from the liquid.
D The skin warms because the most energetic molecules remain in the liquid.

A knife is being sharpened on a rotating sharpening stone. A spark flies off and lands on the operator’s hand. The spark is very hot, very small piece of metal. The operator feels nothing.
What does this show about the piece of metal?
A It has a high thermal capacity.
B It has low thermal capacity.
C It is a good conductor of heat.
D It is a poor conductor of heat.

How does heat from the sun reach the Earth?
A Conduction only
B Convection
C Radiation only
D Conduction, convection, and radiation

2007-03-22 07:59:08 · 6 answers · asked by Jaimee Ariane 3

2007-03-22 07:36:51 · 4 answers · asked by noah 1

I think that means zero molecular or quantum activity, is that right?

2007-03-22 07:36:11 · 7 answers · asked by Chris cc 1

2007-03-22 07:35:26 · 7 answers · asked by So_Needless_2_Say 2

I am working on a problem where a button is placed on a turntable spinning in uniform circular motion. The turntable can be brought up to 40 revolutions per minute without the button slipping, provided it is no more than 0.150m from the center.


I am supposed to find the coefficient of static friction based on this information. Does this mean that the coefficient of static friction changes based on how far away the object is from the center? Am I supposed to be finding a formula for the coefficient in terms of radius R, or is there a fixed coefficient between the button and turntable no matter where the button is placed?

Assuming I've done my calculations right, I came up with coefficient of static friction = 1.79R. Is this my answer, or should I use the information in the question (Rmax=0.150m) to come up with 0.269?

Constructive feedback would be appreciated!

2007-03-22 07:14:25 · 3 answers · asked by wtfroflwafl 1

Let’s push a crate of mass 10.0 kg slowly (at constant speed) up a slope with a coefficient of friction µ. The work we
need to achieve this is 4.00 × 10^2 J. By pulling the crate from this point back down the slope to the original position
we do work of 2.50 × 10^2 J.
The force of both pushing and pulling is parallel to the direction of the slope.
(a) Compare the pushing and pulling forces required.
(b) Consider the work done by the person in moving the crate, and the changes in energy of the crate to calculate:
(i) the amount of energy dissipated by friction as the crate slides either up or down the slope;
(ii) the height difference the crate moves through when sliding along the slope.

2007-03-22 07:06:14 · 3 answers · asked by kate 1

2007-03-22 07:02:15 · 5 answers · asked by woodsonhannon53 6

The net force acting on a 6.0-kg object is given by Fx = (10 - x) N, where Fx is in newtons and x is in meters. How much work is done on the object as it moves from x = 0 to x = 10 m?

2007-03-22 06:22:17 · 1 answers · asked by Devin B 1

What is the difference between engineering and applied physics? Is engineering better than applied physics?

2007-03-22 06:20:56 · 2 answers · asked by Jean 1

from lab involving spinning a stopper on string with varying dangling mass...

briefly explain the relationship between the centripetal force an the amount of hanging weight. why should they be equal?

2007-03-22 05:33:36 · 4 answers · asked by frank8712000 1

A 45 kg trunk is pushed 5.2 m at constant speed up a 30° incline by a constant horizontal force. The coefficient of kinetic friction between the trunk and the incline is 0.24.

Calculate the work done by the applied horizontal force.

Calculate the work done by the weight of the trunk.

How much energy was dissipated by the frictional force acting on the trunk?

Now suppose the 45 kg trunk is pushed 5.2 m at constant speed up a 30° incline by a force along the plane (not as in the figure). The coefficient of kinetic friction between the trunk and the incline is 0.24.

Calculate the work done by the applied force.
Calculate the work done by the weight of the trunk.
How much energy was dissipated by the frictional force acting on the trunk?

2007-03-22 05:29:50 · 1 answers · asked by whaler1963 1

I got a question:

You are an astronaut who has been sent to a large rocky asteroid which is essentially spherical in shape. You are standing on the surface of the asteroid and you need to make an estimate of its radius, R_a. You know that the density (rho)
(density is the mass per unit volume of a substance) of the
asteroid is 2.80 x 10^3 kg m^-3 and that this density is uniform throughout.
You have equipment that enables you to measure the time it takes for a small object to fall from rest through a distance of 1.00m. Your measurement is 4.20s

(a) calculate the acceleration due to gravity g_a at the surface of the asteroid.
You may assume that g_a is constant over the one metre drop in the
experiment.

Can I use the equations of uniform motion for this one? Or do I have to use
density, along with the law of universal gravitation?

(b) Obtain an expression for g_a in terms of the gravitational constant G, the
radius if the asteroid R_a and the density (rho) of the asteroid. Hence
determine R_a. (The volume of a sphere of Radius R is given by 4/3 pi R^3)

Thanks.

2007-03-22 05:27:20 · 4 answers · asked by TJ 2

can we call an area with no matter in it but has EM waves passing through it a vacuum?

If possible, we know that EM waves are made of photons(for visible light) that means there are some particles going thru that space. so how can it be a vacuum?

So what exactly is a vacuum?

2007-03-22 05:13:52 · 9 answers · asked by sh 1

The mass of a flywheel is 5.8 10^4 kg. This particular flywheel has its mass concentrated at the rim of the wheel. If the radius of the wheel is 2.8 m and it is rotating at 358 rpm, what is the magnitude of its angular momentum?

2007-03-22 05:09:27 · 2 answers · asked by Anonymous

Under what conditions are the focal length and image distance the same?

2007-03-22 05:09:05 · 3 answers · asked by Anonymous

I'm stumped...

Find the acceleration a of the particle:
Express the acceleration in terms of v_initial, v_final, and s.

2007-03-22 04:58:39 · 1 answers · asked by Anonymous

i want to make a remote control car

2007-03-22 04:54:08 · 1 answers · asked by road t 1

2007-03-22 04:50:05 · 6 answers · asked by klscott2 1

scientists say that we only know about 5% of the matter in the universe. And the remaining 95% is unknown (i think also called dark matter)

So how do we know that 95% is remaining is its really unknown??

2007-03-22 04:39:15 · 4 answers · asked by sh 1

what does acceleration of the gravity means & how do we calculate it???and caculate the acceleration of the earth gravity

2007-03-22 04:27:55 · 5 answers · asked by Anonymous

a 882N man is 1/4 of the way up a 10m ladder that is resting on a smooth frictionless wall. if the mass of the ladder is 343N and the ladder makes an angle of 60deg with the ground, find the force of friction of the ground on the foot of the ladder. Also find the vertical force at point of contact with the ground.

2007-03-22 04:21:01 · 3 answers · asked by Anonymous

2007-03-22 04:13:33 · 1 answers · asked by Anonymous