Physics - October 2007

I'm a right brain superman, left brain cripple and I am just trying to get my head around this physics stuff...so the first theory of relativity is saying that the only way we can be "sync'd up" with REAL TIME is to move at the speed of light, in which case our mass would become infinite and we would be everywhere at once?

2007-10-15 18:41:58 · 2 answers · asked by Micheal M 4

Say that, from my frame of reference, persons A and B are moving perpendicular to the line between them, at the same velocity. Now suppose A shines a light in the direction of B. Since I see A and B moving with the same velocity, they must see each other standing still. Hence, according to A and B, B will see A's light. However, according to me, B is moving, so that by the time the beam reaches where B was when A shone the light, B will have moved and not been able to see it.

How does one resolve this paradox?

2007-10-15 18:32:55 · 3 answers · asked by TravisKidd 1

decrease
increase
remain the same
or none
?

2007-10-15 18:03:47 · 7 answers · asked by Ismene 2

is it true or false that if the volume of an object below the water will equal the volume of water displaced by the object?"

2007-10-15 17:37:31 · 2 answers · asked by Anonymous

MIT has great Electricity/Mag, and Vibration/Waves lectures, posted online in video form. Does there exist, not neccesarily from MIT, that teaches Quantum Mechanics in the same way? Like in video form? Thank yoU!

2007-10-15 17:35:29 · 3 answers · asked by curtdbz 2

A playground is on the flat roof of a city school, 6.00 m above the street below. The vertical wall of the building is 7.00 m high, forming a 1.00 m high railing around the playground. A ball falls to the street below, and a passerby returns it by launching it at an angle of 53.0° above the horizontal at a point 25.0 m from the base of the building wall. The ball takes 2.00 s to reach a point vertically above the wall.
(a) Find the speed at which the ball was launched.
m/s
(b) Find the vertical distance by which the ball clears the wall.
m
(c) Find the distance from the wall to the point on the roof where the ball lands.
m

2007-10-15 17:34:37 · 2 answers · asked by Anonymous

A cannon with a muzzle speed of 995 m/s is used to start an avalanche on a mountain slope. The target is 2000 m from the cannon horizontally and 809 m above the cannon. At what angle, above the horizontal, should the cannon be fired? (Ignore air resistance.)
what degree?

2007-10-15 17:33:36 · 1 answers · asked by Anonymous

A Rocket is tracked by a radar station 6 miles away. When the rocket is 4 miles high its velocity is .5 miles/second. What is the rate of change of the angle.

2007-10-15 16:57:51 · 1 answers · asked by robscianni 1

a pessenger jet in the air increases its speed does the downward force of air on the top of te wings

increase or decrease? does the net lifting force of the air on the wing increase or decrease? (Explain)

2007-10-15 16:39:35 · 1 answers · asked by playboy_kardy25 1

I am wondering if a coiled ribbon type spring has equal the storage potential, or greater, then let's say a rod coil spring, such as what is used on automobile suspensions.

2007-10-15 16:27:29 · 1 answers · asked by sportsman72901 2

Suppose the spring has a spring constant of 492 N/m and the box has a mass of 2.0 kg. The speed of the box just before it makes contact with the spring in 0.36 m/s.

What is the magnitude of the spring's displacement when the spring is fully compressed?

2007-10-15 16:25:40 · 1 answers · asked by txsweetpea512 1

what if there were no sources to help u? (like the internet)

2007-10-15 15:56:16 · 6 answers · asked by Anonymous

Vector A points in the negative y direction and has a magnitude of 7 units. Vector B has twice the magnitude and points in the positive x direction. Find the direction and magnitude of the following vectors.

(a) A + B
___________
___________ ° (counterclockwise from the +x-axis)

(b) A - B
_________
_________° (counterclockwise from the +x-axis)

(c) B - A
___________
___________° (counterclockwise from the +x-axis)

2007-10-15 15:55:42 · 1 answers · asked by shamsan_415 1

i knwo this is a simple question but for some reason i cant get my head around it..grrr

a ten kilogram block of metal measuring 12 cm x 10cm x10cm is suspened from a scale and immersed in water. the 12 cm dimension is vertical and the top of the block is 5 cm bekiw the surface of the water.
a)what are the forces acting on the top and bottom of the block? (use po of 1.0130x10^5N/m^2

b)what is the reading of the spring scale?

c)show that the buoyant force equals the difference between the forces at the top and the bottom of hte block.

thanx for ur help

2007-10-15 15:35:22 · 2 answers · asked by two_quic 1

A superball of mass m is dropped vertically from a height, h. If the impact time with the floor is {delta}t, what is the average force on the ball? (Assume that the superball bounces back to the same height.)

I think the answer is :

(m*(gh)^0.5)/(2*{delta}t)

is this right? if not, what part is wrong?

2007-10-15 15:32:23 · 1 answers · asked by beer drinkers 2

can someone give me an example of and
radiant energy
nuclear energy
mechanical energy
heat energy
sound energy
chemical energy

2007-10-15 15:08:12 · 2 answers · asked by arely42 3

A block of mass 2 Kg is dropped from height h= 40 cm onto a spring of spring constant k=1960 N/m. Find max distance spring is compressed.

2007-10-15 15:07:27 · 1 answers · asked by Mellie G 1

2007-10-15 14:52:44 · 1 answers · asked by britt-britt r 1

A box of mass m is sliding along a horizontal surface.

Part A:(solved)


The box leaves position x = 0 with speed v_0. The box is slowed by a constant frictional force until it comes to rest at position x = x_1.

Find F_f, the magnitude of the average frictional force that acts on the box. (Since you don't know the coefficient of friction, don't include it in your answer.)
Express the frictional force in terms of m, v_0, and x_1.
I figured out answer to be: 0.5*m*v0^2/x1
Part B:
After the box comes to rest at position x_1, a person starts pushing the box, giving it a speed v_1.

When the box reaches position x_2 (where x_2 > x_1), how much work W_p has the person done on the box?
Assume that the box reaches x_2 after the person has accelerated it from rest to speed v_1.
Express the work in terms of m, v_0, x_1, x_2, and v_1.
It has something to do with conservation of energy

2007-10-15 14:52:26 · 4 answers · asked by Madiyar T 1

The drawing shows a collision between two pucks on an air-hockey table. Puck A has a mass of 0.039 kg and is moving along the x axis with a velocity of +5.5 m/s. It makes a collision with puck B, which has a mass of 0.059 kg and is initially at rest. The collision is not head-on. After the collision, the two pucks fly apart with the angles shown in the drawing.

Find the final speed of puck A.


Find the final speed of puck B.

Here is the drawing

http://www.webassign.net/CJ/07_32.gif

2007-10-15 14:32:54 · 1 answers · asked by yefimthegreat 1

A 600 g steel block rotates on a steel table (μk = 0.6) while attached to a 1.0 m long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 4.2 N perpendicular to the tube. The maximum tension the tube can withstand without breaking is 50 N. If the block starts from rest, how many revolutions does it make before the tube breaks?

2007-10-15 14:31:55 · 2 answers · asked by Anonymous

A 110 g ball on a 60 cm long string is swung in a vertical circle about a point 200 cm above the floor. The tension in the string when the ball is at the very bottom of the circle is 3.5 N. A very sharp knife is suddenly inserted, as shown in Figure P7.51, to cut the string directly below the point of support. Where does the ball hit the floor? (Measure from the point where the string was cut and consider right to be the positive direction.)

2007-10-15 14:31:21 · 2 answers · asked by Anonymous

A 28 g ball rolls around a 44 cm diameter L-shaped track, shown in Figure Ex7.16, at 60 rpm. What is the magnitude of the net force that the track exerts on the ball? Rolling friction can be neglected.

2007-10-15 14:30:23 · 2 answers · asked by Anonymous

2007-10-15 14:16:48 · 3 answers · asked by deannahndrsn 2

Two vectors have magnitudes V1 = 2.0 km and V2 = 4.5 km. What are the maximum and minimum magnitudes of their vector sum?
Maximum

Minimum

2007-10-15 14:14:44 · 2 answers · asked by Shawn Carter 1

Two identical blocks of mass m=2.35 kg each start out at rest at height h=1.63m above ground. Block 1 will fall directly down when released. Block 2 will slide down a frictionless ramp of angle 22 degrees. Using Conservation of Energy, (a) find the final speed v of Block 1 in the moment before it hits the ground, and (b) find the final speed v of Block 2 in the moment before it touches the ground.

I've got part (a) I think but I'm not sure, and part (b) is giving me fits. Anyone know how to do something like this?

2007-10-15 14:04:24 · 1 answers · asked by Big Thinker 3

A horizontal rifle is fired at a bull's-eye. The muzzle speed of the bullet is 605 m/s. The barrel is pointed directly at the center of the bull's-eye, but the bullet strikes the target 0.045 m below the center. What is the horizontal distance between the end of the rifle and the bull's-eye?

2007-10-15 13:54:58 · 1 answers · asked by tim w 1

can someone explain what a spring constant is and what the difference is between a small one and a big one?

2007-10-15 13:50:25 · 2 answers · asked by softballkid4ever 2

A physics student pulls a block of mass m = 22 kg up an incline at a slow constant velocity for a distance of d = 3 m. The incline makes an angle q = 30° with the horizontal. The coefficient of kinetic friction between the block and the inclined plane is µk = 0.2.

Picture: https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/Phys1201/fall/homework/Ch-08-Energy-Conservation/block_ramp_friction_spring/9.gif

a) What is the work Wm done by the student?

b) What is the speed v of the block when it first reaches the horizontal surface?

c) What is the spring constant k of the spring?

d) How far up the incline d1 does the block rebound?

2007-10-15 13:41:21 · 1 answers · asked by Anonymous

A man is traveling 9.8 m/s. When he reached his destination he was traveling 31.6 m/s. He knows his acceleratin was 5 m/s (2nd power). How long did it take him to get there. PLEASE SHOW WORK, it will help me do the rest of these questions. Appreciate any help I can get

2007-10-15 12:55:08 · 3 answers · asked by Lexie. 1