Physics - October 2007

Why was mercury used in early barometers instead of another liquid?

2007-10-30 09:22:13 · 5 answers · asked by liltchaser 2

A projectile is fired at an upward angle from the top of a 105 m cliff with a speed of 185 m/s. What will be its sped when it strikes the ground below?(Use conservation of energy and neglect air resistance.)

2007-10-30 09:11:41 · 3 answers · asked by matt c 1

http://i5.tinypic.com/4r1o407.jpg

Two pucks slide down inclined plane.
Puck A starts from rest.
Puck B is given initial sidewise velocity
(that is in horizontal direction) Vo = 5m/s.

Which puck will reach the bottom (marked as blue line) faster?

2007-10-30 08:53:35 · 1 answers · asked by Alexander 6

The determined Wile E. Coyote is out once more to try to capture the elusive Road Runner. The coyote wears a new pair of Acme power roller skates, which provide a constant acceleration of 15 m/s^2. The coyote starts off at rest 70 m from the edge of a cliff at the instant the road runner zips by in the direction of the cliff.

a.) If the Road Runner moves constant, find the minimum speed the roadrunner must have in order to reach the cliff before the coyote.

b.) If the cliff is 100 m above the base of a canyon, find where the coyote lands in the canyon. (Assume that his skates are still in operation when he is in flight and that his horizontal component of acceleration remains constant at 15 m/s^2).



thx people

2007-10-30 08:31:57 · 1 answers · asked by acousticplaya90 1

As a logging truck rounds a bend in the road, some logs come loose and begin to roll without slipping down the mountainside. The mountain slopes upward at 48.0 degrees above the horizontal, and we can model the logs as solid uniform cylinders of mass 525 kg and diameter 1.20 m.

Find the acceleration of the logs as they roll down the mountain.

What is the friction force on the rolling logs?

2007-10-30 08:23:24 · 1 answers · asked by ! 2

A car rounds a banked curve where the radius of curvature of the road is R, the banking angle is , and the coefficient of static friction is µ.
(a) Determine the range of speeds the car can have without slipping up or down the road. (Use mu for µ, theta for , and R and g as appropriate in your equations.)
minimum speed ----m/s
maximum speed ----m/s

(b) What is the range of speeds possible if R = 150 m, = 10°, and µ = 0.13 (slippery conditions)?
minimum speed ----m/s
maximum speed ---- m/s

2007-10-30 07:57:33 · 1 answers · asked by roxy_799 1

or at least hover a bit. I've seen those guys that strap wings to their arms and jump of a pier, but they don't seem to get much speed up on the flapping.

2007-10-30 07:53:51 · 7 answers · asked by Anonymous

2007-10-30 07:23:30 · 1 answers · asked by Tommy 2

2007-10-30 07:22:58 · 5 answers · asked by ♥ Tori ♥ 5

when the clock goes back an hour what happens at 12 midnight? do we have 2 hours of 11 o'clock. i don't understand or do we have two hours of 12 midnight?

2007-10-30 07:16:59 · 14 answers · asked by laughing_stock 1

http://img248.imageshack.us/img248/1639/cylinderjl0.jpg

A uniform cylinder with a radius of R and mass M has been attached to two cords and the cords are wound around it and hung from the ceiling. The cylinder is released from rest and the cords unwind as the cylinder descends.
(a) draw a proper free body diagram for the cylinder;
(b) Apply Newton’s second law to the cylinder;
(c) apply Newton’s second law in rotational form to the cylinder;
(d) the two equations you have written so far
contain three unknowns; what is the relationship between the linear acceleration of the cylinder and its angular acceleration? (e) Solve for the linear acceleration of the cylinder; (f) What is the tension in the cords?

2007-10-30 07:09:11 · 2 answers · asked by nebulus9 2

1. While chopping down his father's cherry tree, George discovered that if he swung the axe with a speed of 25 m/s, it would embed itself 2.3 cm into the tree before coming to a stop
a) If the axe head had a mass of 2.5 kg, how much force was the tree exerting on the axe head upon impact? Explain your answer.
>>>I have no idea how to do this...
b) How much force did the axe exert back on the tree? Explain your answer.
>>>I have no idea how to do this either......

2. Jackson's favorite ride in Disneyland is the rollercoaster. The rollercoaster car and passengers have a combined mass of 1620 kg, and they descend the first hill at an angle for 45.0 degrees to the horizontal. With what force is the rollercoaster pulled down the hill?
>>I need help with this... T__T

2007-10-30 06:49:49 · 3 answers · asked by Anonymous

a zookeeper shoots a dart horizontally at a monkey. at the same instant, the monkey begins to fall from the tree. Will the dart hit the monkey?

2007-10-30 06:47:19 · 4 answers · asked by Anonymous

What is the intensity?

2007-10-30 06:35:50 · 1 answers · asked by kntagler 1

Can I have a scientific explanation why and how metal expands?

2007-10-30 06:13:12 · 6 answers · asked by Anonymous

im having trouble with this so please explain it to me

a cat ran the distance (d) over a period of time (t) .
if the cat's kinetic energy was (j) whats the formula to find the cat's mass ?

2007-10-30 05:35:46 · 5 answers · asked by Anonymous

2007-10-30 05:31:46 · 5 answers · asked by krstilyzed 1

When a 2-dimensional cone passes through a 2-dimensional plane, the result is a single expanding circle. So, here's my question: Will a 3-dimensional cone passing through a 3-dimential space result in a 3-dimensional expanding "universe"?

2007-10-30 05:21:54 · 2 answers · asked by I'm an Atheist 3

2007-10-30 05:06:53 · 1 answers · asked by Shawna 1

hie guys im studying medical physics and i would need your help on a certain question .

Q: Describe the energy changes that occur in the stages of x-ray production and use .

2007-10-30 05:03:24 · 4 answers · asked by gina 2

A rotating star collapses under the influence of gravitational forces to form a pulsar. The radius of the star after collapse is 1 10-4 times the radius before collapse. There is no change in mass. In both cases the mass of the star is uniformly distributed in a spherical shape.
(a) What is the ratio of the angular momentum of the star after collapse to before collapse?


(b) What is the ratio of the angular velocity of the star after collapse to before collapse?


(c) What is the ratio of the rotational kinetic energy of the star after collapse to before collapse?


(d) If the period of the star's rotation before collapse is 5.00 107 s, what is its period after collapse?

2007-10-30 04:46:28 · 2 answers · asked by sportzblock 1

I have neighbours above and below my flat and every time something, even as small as a pin, drops on the floor upstairs I can hear it in my room with the door shut. Downstairs, there is a boy who likes to shoot a tennis ball at their ceiling( my floor level) but I have never heard the sound of the ball hitting the ceiling. While at the boy's flat one day I noticed that the ball made considarable noise much more than a dropt pin. In my previous flat I always heard noise from upstairs too. Now, back in my room, my head is about the same distance away from the floor as it is from the ceiling. I do not hear the noise from the ball hitting the ceiling downstairs, but that of a dropt pin on the floor upstairs. Does it mean that the noise/sound is heavy so that gravity pulls the sound of the ball downwards and I can therefore not hear it in my room? If this is true why do our cel phone calls go through despite the fact that they have to reach the transmiters against gravity?

2007-10-30 04:36:50 · 5 answers · asked by Sheng Lee 2

A substance classified as a fluid contains particles that
a. quickly expand into any available space.
b. are held in fixed positions.
c. may slide past each other.
d. are very far from each other.

2007-10-30 04:32:44 · 1 answers · asked by -BrownEyedBeauty- 1

What else produces Gamma rays?

2007-10-30 04:20:02 · 1 answers · asked by spencer 2

i will be greatfully thanks if u answered just make it fast

2007-10-30 04:16:50 · 2 answers · asked by knowledge hunter 1

So first of all look at this img :
http://aycu35.webshots.com/image/31034/2003792274542358389_rs.jpg

OK now as u can see , there are 2 different lenses in the picture one is biconvex and the other one is biconcave . Since u already know that lets get to the point .

Since i am a novice in this catagory , and the teacher promiced to give an A+ to whoever solved this 1st , i beg you to help me find the FOCAL point in both cases .


Thank you all , cheers if u solved it . An img response with a little explaning will do very good .

2007-10-30 04:00:29 · 1 answers · asked by Simon T 2

If a car is moving around a circular track in uniform circular motion, with friction present, and a free-body diagram is drawn showing all the forces on the car (3 total forces), then why does the force of the friction, which is parallel to the surface always have a perpendicular or normal force, which is of course perpendicular to the force of friction? I know that there is a force of gravity downward which acts as the opposing force of the earth pushing up on the car, but HOW IS THE FORCE FROM THE TRACK on the car RELATED TO THE FORCE OF FRICTION, AND WHY ARE THE TWO DIFFERENT FORCES PERPENDICULAR. Thanks.

2007-10-30 03:37:41 · 2 answers · asked by M4tr!x 2

Is it possible that hot objects repel colder objects and cold
objects are attracted to hot objects ? This may explain how
the planets rotate around the sun and how moons rotate around
planets. When the opposing forces equal out they find their orbit.

2007-10-30 03:34:17 · 4 answers · asked by Ken 1

2007-10-30 03:21:42 · 12 answers · asked by Anonymous

2007-10-30 02:35:46 · 7 answers · asked by Anonymous