Physics - October 2007

2007-10-10 16:46:59 · 3 answers · asked by Jonathan P 1

Several questions in my homework that i just could not figure out. please help (:

formulas::

vertical
distance= 1/2 * g * t^2
velocity= g * t

horizontal
distance= v * t
velocity= d/t

2. In baseball, a fastball takes about 1/2 seonds to reach the plate. Assuming that such a pitch is thrown horizontally, compare the distance the ball falls in the first 1/4 seconds with the distance it falls in the second 1/4 seconds.

5. a quarterback threw a football at 24 m/s at a 45 angle. If it took the ball 3 seconds to reach the top of its path, how long was it in the air?

2007-10-10 16:36:35 · 1 answers · asked by kiwi 1

Pull a swing or pendulum to one side, let it go and it will swing back and forth by itself. As it goes back and forth the swing is conserving:

a) angular and linear momentum
b) only angular momentum
c) only linear momentum
d) neither angular momentum nor linear momentum

2007-10-10 16:32:04 · 3 answers · asked by ? 6

2007-10-10 16:31:38 · 3 answers · asked by Anonymous

2007-10-10 16:15:16 · 4 answers · asked by jetengine767 3

2007-10-10 16:10:53 · 0 answers · asked by jake1414 1

I've always wanted to see and atom, is it possible, or can we only detect the light around an atom? We seem to have a fair understanding of atoms, so someone must have seen one.

2007-10-10 16:06:13 · 4 answers · asked by Clandestine 1

Then How is the Fermi Energy Level located above the Valence Band in the Energy band model?

Correct me if Im Wrong, but...at Absolute Zero, there are No free electrons, so All electrons Must be located in the Valence Band...

2007-10-10 15:33:57 · 2 answers · asked by kennyk 4

please answer this problem and help me understand what to do:

A skater glides off a frozen pond onto a patch of ground at a speed of 1.8 m/s. Here the skater is slowed at a constant rate of 3.00 m/s^2. How fast is the skater moving when she slid 0.37m across the dirt patch?

i really need some help underdtanding these kind of problems. please help, thanks :)

2007-10-10 15:25:00 · 1 answers · asked by Anonymous

It has been suggested that rotating cylinders about 12 mi long and 6.3 mi in diameter be placed in space and used as colonies. What angular speed must such a cylinder have so that the centripetal acceleration at its surface equals the free-fall acceleration on Earth?
? rad/s

2007-10-10 15:03:03 · 1 answers · asked by Anonymous

Find the centripetal accelerations at each of the following points due to the rotation of Earth about its axis.
(a) a point on the Equator of Earth
? m/s2
(b) the North Pole
? m/s2

2007-10-10 15:02:15 · 3 answers · asked by Anonymous

1)Surprisingly, very few athletes can jump more than 2.2 ft (0.68 m) straight up. Use d = 1/2 gt2 and solve for the time one spends moving upward in a 2.2 foot vertical jump. Then double it for the "hang-time" -- the time one's feet are off the ground.


2)A car takes 10 s to go from v = 0 to v = 30 m/s at approximately constant acceleration. If you wish to find the distance traveled using the equation d = 1/2 at2, what value should you use for a?

3)What is the acceleration of a vehicle that changes its velocity from 130 km/h to a dead stop in 13 s?

2007-10-10 14:43:18 · 1 answers · asked by eaglesblueflag 1

measuring matter

2007-10-10 14:36:50 · 7 answers · asked by ROCHELLE Y 1

Is it the electron orbital? Please help!

2007-10-10 14:34:17 · 3 answers · asked by Claire 3

2007-10-10 14:30:28 · 1 answers · asked by ROCHELLE Y 1

A bucket of water with mass 6.40 kg is accelerated upward by a cord of negligible mass whose breaking strength is 65.0 N .

2007-10-10 14:04:13 · 2 answers · asked by Anonymous

A 1000 N crate is being pushed across a level floor at a constant speed by a force of 500 N at an angle of 20.0° below the horizontal. Need help finding coeficient of kinetic friction between the floor and the crate. explanation would also be very helpful and appreciated.

2007-10-10 14:04:05 · 1 answers · asked by caycetw23 1

A spacecraft descends vertically near the surface of Planet X. An upward thrust of 25.0 kN from its engines slows it down at a rate of 1.20m/s^2, but if an upward thrust of only 10.0 kN is applied, it speeds up at a rate of 0.80m/s^2.

2007-10-10 14:02:17 · 1 answers · asked by Anonymous

a.)it's possible to have motion in the absence of a force?
b.)if an object isn't moving, no external force acts on it?
c.)if an object is not acceleration, no external force is acting on it.
d.)if the net force acting on an object is in the positive x-direction, the object moves only in the positive x-direction.

2007-10-10 13:51:54 · 3 answers · asked by ? 2

1. How much work is done when a weight lifter holds a 5KG barbell over his head at a height of 10m for 50s?

Givens:

m = 5KG
d = 10m
t = 50s

Where m is mass, d is distance, and t is time.

The formula for work is W = FD; W is work, F is force, and D is distance.

2007-10-10 13:40:17 · 1 answers · asked by killerwu753 1

how would the capacitance, charge of each plate, and potential difference between two plates change? or any of these change at all?

2007-10-10 13:37:36 · 1 answers · asked by jkim972 3

(a) acceleration
(b) distance
(c) velocity
(d) speed

Which is the answer? And why? What does it mean "time-rate of change"?

2007-10-10 13:31:09 · 1 answers · asked by James 1

what is the relationship between the movement of the wave and the movement of the particles o the mudium ?

2007-10-10 13:19:21 · 1 answers · asked by lzp93627 1

Consider the 662N weight held by 2 cables... The left hand cable had tension T and makes an angle θ with the wall. The right hand cable had tension 860N and makes and angle of 32 degrees w/ the ceiling.

- What is the tension T in the left hand cable slanted at an angle θ w/ respect to the wall?


- What is the angle θ wich the left hand cable makes w/ respect to the wall?


**I understand the problem if the angles were given - but how could you find the tension w/o the angle???

2007-10-10 13:00:29 · 2 answers · asked by Anonymous

I'm not sure how to go about answering this. Any help would be appreciated.

A ball is projected horizontally from the edge of a table that is 1.00m high, and it strikes the floor at a point 1.20m from the base of the table.
a.) What is the initial speed of the ball?
b.) How high is the ball above the floor when its velocity vector makes a 45.0 degree angle with the horizontal?

2007-10-10 12:58:57 · 2 answers · asked by neverisenough 1

A truck, carrying a sheet of plywood, accelerates at 1.8 m/s2. When the truck's speed reaches 20 m/s, the sheet of plywood falls off the back of the truck. The truck continues to accelerate forward at 1.8 m/s2, but the plywood slides on the road with an acceleration of -0.85 m/s2. What is the distance between the truck and the piece of plywood 5.0 seconds after the plywood falls off the truck?

2007-10-10 12:53:06 · 1 answers · asked by alkesh831 2

Gandalf the Grey started in the Forest of Mirkwood at a point with coordinates (2, 1) and arrived in the Iron Hills at the point with coordinates (4, 5). If he began walking in the direction of the vector v=3i+2j and changes direction only once, when he turns at a right angle, what are the coordinates of the point where he makes the turn.

I can do this by using equation of lines.. but I have no idea how to do this with vectors.

2007-10-10 12:50:46 · 1 answers · asked by Zajebe 2

If I could get any help with any of these questions, it would be much appreciated. These deal with projectiles and vertical/horizontal displacement.

1) The peregrin falcon flies at speed of 200 mph. Assume it moves horizontally at this speed 100 m above the ground when it brings its wings into its sides and freefalls. How far will the bird fall vertically while traveling horizontally a distance of 100 m? (Answer: 6.13 m just need work, please)

2) A puma jumps to a height of 12 feet when leaving the ground at an angle of 45 degrees. With what speed must it leave the ground to reach this height? (Answer: 12 m/s work or rational behind it needed)

Again, any help would greatly be appreciated! Thanks in advance.

2007-10-10 12:48:12 · 1 answers · asked by yankeesrus07 2

I just finished watching a NOVA program titled E=MC2, the narrator stated that Einstein had discovered that mass and enegy is the same thing, in different forms. If this is entirely accurate, how do you account for gravity, energy has no gravity, to my knowledge, if it did, the incredible gravity of the singularity would have prevented its expasion. He also stated that the sun loses four million tons of mass each and every second, I know that this is incorrect, that may be the amount of mass that is used to convert hydogen into helium, every second, but only a small portion of this mass is lost in the process of fusion and converted into radiation. Is there something missing in the first statement?

2007-10-10 12:23:00 · 1 answers · asked by johnandeileen2000 7

Fake Coin
Imagine that you have in front of you fifty coins. They all look exactly alike except one of them is a fake. Because it's a fake, it weighs a couple of grams more than a real coin. So, if you had a balance scale, and you knew which one was the bogus coin, you would put it on one side of the scale, and a good coin on the other side. It would be immediately obvious from this imbalance which one was the phony coin, because it's heavier than a real coin. Knowing that, you have in front of you fifty coins -- one of which is bogus and a balance scale. The question is: how can you determine which one is the fake in four attempts?

2007-10-10 12:19:39 · 1 answers · asked by tuazeee 2