Physics - October 2007

The question is that a mass is shot from a cannon and the end of the cannon's barrel is at a height of 6.9m. The initial velocity vi of the projectile has a horizontal component of 4.6m/s. The projectile rises to a maximum height of delta y above the end of the cannon's barrel and strikes the ground a horizontal distance delta x past the end of the cannon's barrel and the acceleration of gravity is 9.8m/s^2. I have to find the time it takes for the projectile to reach its maximum height in seconds. I used vy^2=voy^2-2g(y-yo) and I get 7.6 but it's not the right answer if someone knows what I did wrong that would be so helpful.

2007-10-16 14:27:17 · 1 answers · asked by glance 3

A 0.8 kg tennis ball is dropped from rest at a height of 5.6 m onto a hard floor.

a) What is the speed of the ball at the instant of contact with the floor?

|v| = m/s
A flash photograph shows that the ball is compressed a maximum of 0.6 cm when it strikes the floor. b) Assuming that the acceleration of the ball is constant during its contact with the floor, what force does the floor exert on the ball?

|f| = N
c) Over what time does the force act in bringing the ball to rest?

D t = s

2007-10-16 14:25:27 · 1 answers · asked by cuteeebabygirl 1

How do you find the kinetic energy of a 27 kg gun that has just fired a 52.2g bullet with a velocity of 317 m/s.

If the momentum of the bullet is 16.547 kg*m/s shouldt the momentum of the gun be the same?

2007-10-16 14:11:53 · 1 answers · asked by finding.4ever 1

Looking through a spectroscope at a candle, hyrogen lamp, sun, and incendessent light bulb, I noticed they did not have the same wavelength of colors even though they are all forms of light. How come they differ?

2007-10-16 14:00:00 · 3 answers · asked by Anonymous

Physics question relating to wave interference. (Please include several links explaining your answers.)

2007-10-16 13:58:47 · 2 answers · asked by Tony 2

A child's pogo stick (Fig P5.75) stores energy in a spring (k = 2.60 104 N/m). At position A (x1 = -0.100 m), the spring compression is a maximum and the child is momentarily at rest. At position B (x = 0), the spring is relaxed and the child is moving upward. At position C, the child is again momentarily at rest at the top of the jump. Assume that the combined mass of child and pogo stick is 25.0 kg.

Fig P5.75 http://www.webassign.net/sercp/p5-75.gif

(a) Calculate the total energy of the system if both potential energies are zero at x = 0.
J
(b) Determine x2.
m
(c) Calculate the speed of the child at x = 0.
m/s
(d) Determine the value of x for which the kinetic energy of the system is a maximum.
mm
(e) Obtain the child's maximum upward speed.
m/s

2007-10-16 13:48:58 · 1 answers · asked by Anonymous

A 5.0 kg block is pushed 2.0 m up a vertical wall with constant speed by a constant force of magnitude F applied at an angle of = 30° with the horizontal, as shown in Figure P5.70. If the coefficient of kinetic friction between block and wall is 0.30, determine the work done by each of the following.

Figure P5.70 http://www.webassign.net/sf/p5_70.gif


(a) the force
J
(b) gravity
J
(c) the normal force between block and wall
J
(d) By how much does the gravitational potential energy increase during the block's motion?
J

2007-10-16 13:45:31 · 1 answers · asked by Anonymous

Across what potential difference does an electron have to be accelerated in order to reach the speed v = 2 x 10 to the 7 m/s? should you use relativistic calculations?

2007-10-16 13:38:43 · 1 answers · asked by szydzo 1

i just dont know how to find the density of an irregular object
:(

2007-10-16 13:33:42 · 1 answers · asked by kbubles 2

2007-10-16 13:20:25 · 1 answers · asked by CherryGirl 1

...Person and canoe have a combined mass of 105kg. (a) Ignoring air resistance and friction, find the velocity of the canoe after the person throws the stone. (b) With what velocity would the person have to throw the stone in order to get the canoe to move at 1m/s?

the answers are (a) 0.38m/s (b)21m/s but i need the work. can someone help?

2007-10-16 13:04:26 · 4 answers · asked by Danielle M 1

Einstein is about to be proven wrong when he said nothing moves faster than the speed of light. Evidence is mounting to support the above question. Its called The Inflationary Theory. Information about this theory is hard to find, but its out there. Do you think its possible, from a microscopic spec in a fraction of a second? Incredible speed. How would you describe something that moves faster than the speed of light?

2007-10-16 13:02:36 · 2 answers · asked by ZORRO 3

An astronaut on the surface of the Moon fires a cannon to launch an experimental package, which leaves the barrel moving horizontally. Assume that the free-fall acceleration on the Moon is one sixth that on the Earth.
(a) What must be the muzzle speed of the probe so that it travels completely around the Moon and returns to its original location?
km/s
(b) How long does this trip around the Moon take?
h

2007-10-16 12:49:35 · 1 answers · asked by Anonymous

why does the temp continue to rise ?

2007-10-16 12:31:38 · 5 answers · asked by cando 4

I know what they are, where they apply but I can't see why they are seperated into 4 different categories? Is it not all the same force in different concentrations?

2007-10-16 12:22:58 · 5 answers · asked by Anonymous

How do i convert Degrees C/f to degree C/F?

2007-10-16 12:18:05 · 3 answers · asked by Anonymous

2007-10-16 12:08:56 · 3 answers · asked by britt-britt r 1

2007-10-16 11:09:59 · 2 answers · asked by breanna b 1

2007-10-16 11:06:53 · 2 answers · asked by amber_renae_2007 1

What would happen if an immovable object were confronted with an unstoppable force?

2007-10-16 10:58:09 · 10 answers · asked by Anonymous

Lets say I need to find the breaking point of an irregular object,
say a bone. What Kind of Math/Sciences do I need to know to find it?

2007-10-16 10:53:06 · 4 answers · asked by DeathHead 2

2007-10-16 10:30:35 · 1 answers · asked by JAMES 4

2007-10-16 10:08:15 · 8 answers · asked by Mitchell 5

I am wondering about rotation symetry etc

2007-10-16 10:01:12 · 10 answers · asked by Anonymous

MASS. Am i right here about an object needing a large mass to have its own gravity? If not, how large do objects in space need to have gravity. the question came to me when i watching family guy, the one where peter starts a fat people club and brian is trying to prove to peter that he's fat, so he troughs an apple at him than it starts to float around peter like a moon. Than peter still refuses that he's fat so than brian troughs a chair, a tv and a pot and they all start to float around him. it's really funny.
but seriously, how large of a mass does an object have to be to have it's own gravity ( i didn't say volume because look at jupiter, it's big but it doesn't have a super strong gravity while on earth our gravity is greater than jupiters because jupiter is mainly frozen gas and gas where earth is rock and all that other stuff )? And if i'm completely wrong, how does an object get gravity?

2007-10-16 09:40:08 · 4 answers · asked by µMeGA WaTT 3

Are there any known materials besides other magnetic fields that will weaken, block, ect other magnetic fields? I mean in the sense of how lead is used to to weaken or block electormagnetic radiation(i.e. x-rays). Any thing it all will help, thanks.

2007-10-16 09:10:33 · 1 answers · asked by ozzy4president51 or sean 3

2007-10-16 08:30:48 · 3 answers · asked by Alexander 6

When I was a tennager my friends and I would play,once we got the thing moving we could bring our fingers off(just above the glass)and it would still move.Now I know it wasn't "a ghost",so can anybody explain it?

2007-10-16 07:54:09 · 7 answers · asked by 5brats 3

2007-10-16 07:51:58 · 5 answers · asked by Anonymous

sending off 3 bottle rockets of varying weights and timing them. any opinion? or ideas?

2007-10-16 07:41:43 · 2 answers · asked by Heather 3