Physics - February 2007

2007-02-09 19:04:14 · 7 answers · asked by lhens 1

Researching black holes, I read that at certain points within the black hole, called Singularities, the laws of physics do not apply. Is this true, and how can these "laws" truly be called laws, if true?

2007-02-09 18:33:21 · 11 answers · asked by slick j 1

A 1.20 102 kg crate is being pushed across a horizontal floor by a force that makes an angle of 30.0° below the horizontal. The coefficient of kinetic friction is 0.400. What should be the magnitude of , so that the net work done by it and the kinetic frictional force is zero?

2007-02-09 18:06:39 · 3 answers · asked by mark m 1

2007-02-09 17:58:49 · 1 answers · asked by mammu 1

2007-02-09 17:45:19 · 2 answers · asked by joe c 1

a. It decreases
b. Velocity has no impact on momentum.
c. Her momentum equals zero.
d. It converts to impulse

2007-02-09 17:19:26 · 14 answers · asked by joebennett 1

2007-02-09 17:05:53 · 5 answers · asked by wheeliebin 6

2007-02-09 17:02:37 · 1 answers · asked by nat1 1

it take the other side of the pole to move? At exactly the same time, or will there be a delay? If so, how long would the delay be?

2007-02-09 16:58:51 · 7 answers · asked by Source 4

2007-02-09 16:52:31 · 12 answers · asked by joe c 1

a boat has a mass of 6800kg, its engines generate a drive force of 4100N. due west, while the wind exerts a force of 800N.due east and the water exerts a resistive force of 1200N due east.
what is the magnitude and direction of the boats acceleration?

2007-02-09 16:51:35 · 3 answers · asked by tico 1

What charge (magnitude as well as direction) should be placed exactly on the mid point of the line segment joining two identical charges, each with a charge of Q coulombs? Please explain.

[The answer is: -Q/4 coulombs].

2007-02-09 16:00:08 · 4 answers · asked by Kristada 2

I used this to determine the velocity of the putter at the impact point:


PE + KE (top of putter backswing) = PE + KE (bottom of putter swing-when it is vertical and impacting the ball)


H=.055m (this is based on a 20 degree backswing from vertical position)

g=9.8m/s^2

m=.46kg


(H*G*M)+KE(top)= 0+1/2(M)(V^2)

(.055m)(9.8m/s^2)(.46kg) + 0 = 0 + 1/2(.45kg)(V^2)

(.243kg*m^2/S^2)=(.225kg)(V^2)

V=1.05m/s


Coefficient of friction:

.105 for this surface


Impulse time at putter impact with golf ball:

.005 seconds

2007-02-09 15:58:45 · 1 answers · asked by travo 1

I'm specifically wondering about how groscopes are used to control or stabilize something.

2007-02-09 15:47:39 · 2 answers · asked by Anonymous

The question is .....A high school kicker makes a 30.0 yd. field goal attempt (in american football) and hits the crossbar at a height of 10.0 ft. What is the net displacement of the football from the time it leaves the ground until it hits the crossbar? I'm so confused......please help!

2007-02-09 15:33:09 · 5 answers · asked by shontai 3

Generally, an acceleration less than 800 m/s2 lasting for any length of time will not cause injury, whereas an acceleration greater than 1000 m/s2 lasting for at least 1 ms will cause injury. Suppose a small child rolls off a bed that is 0.44 m above the floor. If the floor is hardwood, the child's head is brought to rest in approximately 1.9 mm. If the floor is carpeted, this stopping distance is increased to about 1.2 cm. Calculate the magnitude and duration of the deceleration in both cases, to determine the risk of injury. Assume that the child remains horizontal during the fall to the floor. Note that a more complicated fall could result in a head velocity greater or less than the speed you calculate

hardwood floor magnitude______ m/s2 duration ______ ms

Carpeted floor magnitude_______m/s2 duration ______ ms


really need help on this one guys.
Thanks

2007-02-09 15:03:24 · 2 answers · asked by cosmo 1

2007-02-09 15:03:14 · 5 answers · asked by Lizzie 5

I want to cover a distance of D, and take exactly T time to do it. I want my initial velocity and final velocity to be zero. So, I'll be accelerating for a period <=.5T, maybe coasting for a while, then deccelerating equally and oppositely to my first acceleration. The easiest case to work with is when there's no coasting distance, and that's when the acceleration is a minimum. As my acceleration increases from trial to trial, there's more distance that I coast. I think. What I want is the distance that I coast expressed as a function of my acceleration, or vice versa. If that's possible in terms of T and D, great. If that turns out to be an unholy mess, it's fine if you let them equal one metre and one second, respectively. Thanks, folks!

2007-02-09 14:55:50 · 2 answers · asked by Mehoo 3

On a frictionless surface, a 0.35 kg puck moves horizontally to the right (at an angle of 0°) and a speed of 2.3 m/s. It collides with a 0.23 kg puck that is stationary. After the collision, the puck that was initially moving has a speed of 2.0 m/s and is moving at an angle of −32°. What is the velocity of the other puck after the collision?

2007-02-09 14:47:04 · 1 answers · asked by Chris 1

2007-02-09 14:27:02 · 2 answers · asked by Anonymous

I would like to know; What is the relationship between watts/square centimeter, and the boiling point of water for system pressures between 0 and 40 psi. Also, I'd like to know what the relationship of water flow past the heating element would be for energy densitys above the boiling energy density. Specifically, if I use a heating element that has a watt density above the boiling poine (at 0 pressure), how much flow (past the heating element surface) do I need for various energy densities to not have boiling?

Thank you

2007-02-09 14:05:07 · 2 answers · asked by kelli p 2

Imagine if someone says that they could only understand love if they can put it into some kind of scientific formula, or measure it out to prove it experimentally? “Science “can tell us little about the appreciation of a sunset, about the soul of man or so many other things. For that matter, science can tell us very little about the mind itself.



The thing is, science can only begin after the universe and the creation already exist. Science can tell us nothing about what happens before that. In fact, let me say this; science begins after creation. The first law of physics, conservation of matter and energy says matter and energy can neither be created nor destroyed. This tells you that science does not know how matter came into existence. It should also tell you that if matter cannot be created under the laws of this universe, that something outside the 1st law created matter and energy. The most important law of science itself points to a “special creation” outside of science

2007-02-09 13:47:24 · 11 answers · asked by be my Angel :) 3

2007-02-09 13:22:29 · 16 answers · asked by wencar29 1

On a frictionless surface, a 0.35 kg puck moves horizontally to the right (at an angle of 0°) and a speed of 2.3 m/s. It collides with a 0.23 kg puck that is stationary. After the collision, the puck that was initially moving has a speed of 2.0 m/s and is moving at an angle of −32°. What is the velocity of the other puck after the collision?

2007-02-09 13:08:22 · 1 answers · asked by xiuhcoatl 1

1. The digital displays of watches and other devices are normally polarized. What related problem can occur when wearing polarized sunglasses?

2. Why may an ideal Polaroid filter transmit anything from zero to 100% of incident polarized light?

3. How can you determine the polarization axis for a single sheet of Polaroid?

Thanks =)

2007-02-09 13:06:59 · 2 answers · asked by Anonymous

How much taller is the building when the temperature is T=115 deg F? (The linear expansion coefficient of steel is A=1.1 x 10^-5 (Deg C)^-1.) Answer in units of cm.

2007-02-09 13:00:27 · 2 answers · asked by naids56 2

What is the accelearation of the sphere as it falls through water? Answer in units of m/s^2.

2007-02-09 12:58:50 · 2 answers · asked by naids56 2

Ball A, which has mass 23 kg, is moving horizontally left to right at +7.8 m/s when it overtakes the 67 kg ball B, which is moving left to right at +4.7 m/s, and they collide elastically. (a) What is ball A's velocity after the collision? (b) What is ball B's velocity?

for (a) i keep getting -3.81 and for (b) i keep getting 4
what am i doing wrong?

2007-02-09 12:57:08 · 1 answers · asked by xiuhcoatl 1

A small hoist can raise 102 kg of bricks to the top of a construction project 35 m above the street in half a minute. Determine the power provided.

_____ W

2007-02-09 12:37:58 · 1 answers · asked by Khoi 1

2007-02-09 11:58:09 · 4 answers · asked by Anonymous