Physics - November 2007

If your textbook is in equilibrium, what can you say about the forces acting on it?

2007-11-26 12:34:42 · 1 answers · asked by Anonymous

I know this is not a very hard physics problem but I'm having some trouble figuring out the answer. Does anyone know how to do this?

2007-11-26 12:31:18 · 2 answers · asked by Sean 2

In the movie Jurassic Park, there is a scene in which some members of the visiting group are trapped in the kitchen with dinosaurs outside. The paleontologist is pressing against the center of the door, trying to keep out the dinosaurs on the other side. The botanist throws herself against the door at the edge near the hinge. A pivotal point in the film is that she cannot reach a gun on the floor because she is trying to hold the door closed. If the paleontologist is pressing at the center of the door, and the botanist is pressing at the edge about 6 cm from the hinge, estimate how far the paleontologist would have to relocate in order to have a greater effect on keeping the door closed than both of them pushing together have in their original positions.

2007-11-26 12:26:07 · 2 answers · asked by ? 1

Some enterprising physics students working on a catapult decide to have a water balloon fight in the school hallway. The ceiling is 3 m in height, and the balloons are launched at a velocity of 10 m/s. the acceleration of gravity is 9.8 m/s/s.
At what angle must they be launched to just graze the ceiling? Answer in units of degrees.

2007-11-26 12:15:31 · 2 answers · asked by Anonymous

A 13 kg crate is pulled by a force (parallel to the incline) up a rough incline. The crate has an initial speed of 1.69 m/s. The crate is pulled a distance of 7.41 m on the incline by a 150 N force. The coefficient of friction is 0.328. The acceleration of gravity is 9.8 m/s^2.

(Please help I haven't had any luck with this problem.)

2007-11-26 11:54:15 · 2 answers · asked by margarita_9902@sbcglobal.net 2

A glass ball is immersed into a fluid at two different temperatures t 1 =17 degrees C and t 2 = 20 degrees C. At t1 the ball displaces the mass of fluid m 1 = 30.10 g and at t 2, m 2 = 30.01 g. Calculate the difference between the coefficient of volume thermal expansion of the fluid and the corresponding coefficient for glass.
Give your answer with 3 sig. fig. in scientific notation.

2007-11-26 11:43:09 · 1 answers · asked by Anonymous

A motorcycle has a constant speed of 25m/s as it passes over the top of a hill whose radius of curvature is 126m. The mass of the motorcycle and driver is 342kg. Find the magnitude of
(a) The centripetal force
(b)the normal force that acts on the cycle

A motorcycle is traveling up the sude of a hill and down the other side. the crest is a circular arc with a radius of 45m. Determine the maximum speed that the cycle can have while moving over the crest without losing contact with the road.

Thank You!

2007-11-26 11:34:31 · 2 answers · asked by Anonymous

Background info: A spring oscillates with a weight on it in simple harmonic motion.
This is another physics lab question.... please help!

2007-11-26 11:21:47 · 1 answers · asked by Anonymous

A 6.0 g coin sliding to the right at 20.0 cm/s makes an elastic head-on collison with a 12.4 g coin that is initially at rest. After the collision, the 6.0 g coin moves to the left at 11.0 cm/s.
(a) Find the final velocity of the other coin.
(b) Find the amount of kinetic energy transferred to the 12.4 g coin.

2007-11-26 11:13:30 · 1 answers · asked by Anonymous

What is absolute zero exactly, and is it impossible to reach? If one were to magnify this temperature to a massive scale, and you, in part, stop time?

2007-11-26 11:11:51 · 5 answers · asked by Lobo man 2

A 11.8 g bullet is fired horizontally into a 94 g wooden block initially at rest on a horizontal surface. After impact, the block slides 7.5 m before coming to rest. If the coefficient of kinetic friction between block and surface is 0.650, what was the speed of the bullet immediately before impact?

i got 1.1 as an answer but that is not right.
i don't know how to do this so any help is appreciated.thanks.

2007-11-26 11:11:17 · 1 answers · asked by loveall 3

Janet jumps off a high-diving platform with a horizontal velocity of 2.8 m/s and lands in the water 2.6 s later.

How high is the platform and how far from the base of the platform does she land?

2007-11-26 11:05:46 · 1 answers · asked by bebostep 2

2007-11-26 10:47:59 · 2 answers · asked by Yahoo! 5

I found the first part.

Please read the question:

A block of mass 15 kg starts from rest and slides a distance of 6 m down an inclined plane making an angle of 40 degrees with the horizontal. The coefficient of sliding friction between block and plane is 0.4 .
The acceleration of gravity is 9.8 m/s^2.

Question one - What is the net force on the block along the incline? answer in units on N.

Answer - I know the answer to question one is 49.446365.

HERE IS THE HELP I NEED

QUESTION 2 - What is the speed of the block after sliding 6 meters? Answer in units of m/s.

QUESTION 3 - What would be its speed if friction were negligible? Answer in units of m/s.

APPRECIATE EVERYONES HELP!!!!!

THANK YOU!!!!

2007-11-26 10:45:30 · 1 answers · asked by mimi j 1

William tell is shooting at an apple hanging in a tree. The apple is a horizontal distance of 20 m away and at a height of 4 m above the ground. If the arrow is released from a height of 1 m above the ground and hits the apple .5 s later, what is the initial velocity?

2007-11-26 10:35:25 · 3 answers · asked by Anonymous

What causes curved space?

2007-11-26 10:19:54 · 6 answers · asked by Yahoo! 5

2007-11-26 10:01:54 · 3 answers · asked by Anonymous

2007-11-26 09:48:44 · 2 answers · asked by Alexander 6

2007-11-26 09:28:10 · 16 answers · asked by Anonymous

Light power it's measured in Watts/stereoradian but this is not sufficient to measure the human perception of light so it's "invented" the candela, which has to do with the “light sensitivity function”.

So it happens with sound. We perceive sounds with same power but different frequency as if they had different intensity. So it’s invented the loudness or the dBA which consists on adding or subtracting dB to the real intensity so we obtain loudness.

The difference between this two facts is for mi very big: light has to be measured with a new basic unit (candela) but sound can be measured just adding or subtracting to the real measurement (in dB’s) a factor given in a chart (in dB’s too) obtaining dBA which is not actually a new unit.

My question(s) (at last!) is(are):

Couldn’t be the light measured just with a correction factor as it’s done with sound so we didn’t have to use the candela?

Could be defined a new basic unit to express the loudness?

2007-11-26 09:12:58 · 2 answers · asked by JPM 1

Does his impression of me really matter or does he just go by the transcripts?

The meeting is about what classes I will need to take to get a second Bachelors in Physics. The way I see it, the meeting is just a formality but I could be wrong.

2007-11-26 09:04:35 · 7 answers · asked by Anonymous

Case 1 and case 2 show two situations of a block hanging
from a string wrapped around the outside of a pulley. The
blocks are identical, and the pulleys are uniform solid
disks of the same radius, but the pulley in case 2 has twice
the mass (and therefore twice the moment of inertia) of
the pulley in case 1. The systems are released from rest at
the same time from the same height above the ground, and
in both cases the block accelerates down. Neglect friction.

(a) In which case is the acceleration of the block
larger?

(b) In which case is the tension in the string, while the block is falling, larger?

(c) In which case is the net torque on the pulley, while the block is falling, larger?

(d) In which case does the block have a higher speed after falling through a distance h?

(e) In which case does the pulley have a larger rotational kinetic energy, measuring the
kinetic energy at the instant the block reaches the ground in each case?

2007-11-26 09:00:25 · 1 answers · asked by yep 1

i have not been given anything or told anythign for that sake...i need 2 find teh internal resistance of a solar cell and vary the light intensity if i have time... i dont understand how to go about it..what to use..the digital meter???? e.t.c plz help me as soon as possible..thank you very much...n oh yh plz explain it in laymen terms :D thank you so much

2007-11-26 08:47:06 · 2 answers · asked by BaByXx L 1

2007-11-26 08:39:35 · 3 answers · asked by cerelac 2

Why can a rocket accelerate into space when the force of takeoff remains the same?
-the rocket is on a launch pad

2007-11-26 08:39:00 · 5 answers · asked by Anastasia B 2

2007-11-26 08:31:11 · 3 answers · asked by alexxandra_1 1

A uniform solid sphere with a mass of M = 5.0 kg and radius R = 20 cm is rolling without
slipping on a horizontal surface at a constant speed of 5.0 m/s. It then encounters a ramp, and
proceeds to roll without slipping up the ramp. The goal of this problem is to determine the
maximum height reached by the sphere on the ramp before it turns around, and to use
conservation of energy to do so. Use g = 10 m/s2.

(a) Write out expressions for the remaining terms. Remember to account for both
translational kinetic energy and rotational kinetic energy, if appropriate. Keep everything in
terms of variables.

(b)How far does the sphere roll up the ramp (measuring the vertical distance)? First
find an expression for this distance in terms of variables, simplified as much as possible, and
then plug in the appropriate values.

(c) If a block slides without friction up the ramp, starting at the bottom with the same
initial speed as the sphere, which object travels farther up the ramp

2007-11-26 08:13:17 · 1 answers · asked by yep 1

So, I need to know the general way to find the ground state energy, but I've provided an example problem so you know what I'm asking.

You have a cold gas of atoms, and you observe that if you shine light consisting of photons with energy 6 eV or greater through the gas, some free electons are observed, implying that photons of such energies are able to ionize an atom in the gas (that is, separate an electron from an atom). You find that with photons of less than 6.0 eV, no ionization occurs.

What is the energy of the ground state? K+U=?

So I really really need to know this for the exam, and I somehow missed it. If anyone could please give an explanation (the answer is -6 eV), I would be very very appreciative. :-D

2007-11-26 07:58:34 · 2 answers · asked by Anonymous

If so, then how can we keep time travel a secret, for example, if I met my father in 1969 on the day he graduated high school?

2007-11-26 07:55:23 · 3 answers · asked by Yahoo Man 1

(a) Calculate the gravitational potential energy of a 2 kg mass on the surface of the Earth.
J
(b) Calculate the gravitational potential energy at an altitude of 22 km.
J
(c) Take the difference between the results for parts (b) and (a), and then compare this with mgh, where h = 22 km.
J (difference between parts a and b)
J (mgh)

2007-11-26 07:42:18 · 2 answers · asked by Amber G 2