Physics - December 2007

1. A figure skater begins spinning counterclockwise at an angular speed of 4.0 "PIE" rad/s. During a 3.0 s interval, she slowly pulls her arms inward and finally spins at 8.0 "PIE" rad/s. What is her average angular acceleration during
this time interval?
2. What angular acceleration is necessary to increase the angular speed of a fan blade from 8.5 rad/s to 15.4 rad/s in 5.2 s?

2007-12-17 18:19:55 · 1 answers · asked by Qasim S 1

in optics

2007-12-17 17:52:52 · 5 answers · asked by ana a 1

PLEASE HELP ME OUT FOR DERIVATION OF E=MC^2

2007-12-17 17:25:11 · 1 answers · asked by Joshua 2

2007-12-17 16:08:53 · 3 answers · asked by coolgal 1

horizantal surface, a force of 10 newtons is required. The force of friction between the surface and the object is....?

What is a equation i can use for this?

2007-12-17 15:44:50 · 5 answers · asked by Anonymous

He had an honorable Ph.D degree from Princeton University.

2007-12-17 15:32:23 · 3 answers · asked by chanljkk 7

2007-12-17 15:05:03 · 5 answers · asked by alanaeichner 1

If the wind is blowing from the NW at 30 knots, calculate the pressure on the body of one of the campus figures facing the wind and, from this, calculate the torque on the welded feet.

2007-12-17 14:55:08 · 1 answers · asked by Heavy-Metal123 3

In other words, does the sun's heat get reflected more or obsorbed more?

2007-12-17 14:54:23 · 2 answers · asked by Anonymous

• Which units are derived units? Which are fundamental units?
• Which are vectors, scalars?
• What’s slope of position vs time graph? Is this quantity average or instantaneous?
• Determine the relative momentum of 2 colliding objects.
• What are MKS units for mechanical power?
• According to newton’s law of universal gravitation, describe proportionality relative to the masses of 2 objects.
• According to newton’s law of universal gravitation describe proportionality relative to distance b/t objects.
• Which law is the statement, “ the force of attraction b/t 2 objects is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance b/t their distance of mass”
• Which angle maximizes the range of the projectile.
• If friction force double how long it take to come to rest compared to not doubled friction force
• What’s the resultant force when pulling 2 ropes one 50N north other 30N east? 20N NW????
• What’s tendency of an object to resist change in motion?
• Which 2 angles of projectile motion result in projectile landing in same place?
• To cross flowing river which directions for least time and least distance?
• Crate dropped from plane when box hits where will it be relative to the plane with no air friction?
• What are 2 vectors in the horizontal and vertical directions that replace single vector?

2007-12-17 14:40:13 · 2 answers · asked by j91621 2

2007-12-17 13:27:21 · 3 answers · asked by pedram m 1

The front of a 1200 kg car is designed to absorb the shock of a collision by having a "crumple zone" in which the front 1.20 m of the car collapses in absorbing the shock of a collision.

(a) If a car traveling 26.0 m/s stops uniformly in 1.20 m, how long does the collision last?
answer in s

(b) What is the magnitude of the average force on the car?
answer in N
(c) What is the acceleration of the car in g's?
answer in g

2007-12-17 13:16:03 · 1 answers · asked by kagekiri_tora 2

Why is it hurt if it does so while carrying a heavy load? which of Newton's Law ismost applicable here???


Please help me. .
thanks!

2007-12-17 13:12:01 · 1 answers · asked by Anonymous

http://class.phys.psu.edu/SampleExams/p212SampleExams/MT2/p212_MT2_S1.pdf

2007-12-17 12:42:42 · 1 answers · asked by Anonymous

A child and sled with a combined mass of 48.6 kg slide down a frictionless hill that is 8.02 m high. If the sled starts from rest, what is its speed at the bottom of the hill?

and

A person doing a chin-up weighs 755 N, disregarding the weight of the arms. During the first 25.0 cm of the lift, each arm exerts an upward force of 381 N on the torso. If the upward movement starts from rest, what is the person's speed at this point?

2007-12-17 12:39:14 · 1 answers · asked by Anonymous

At what coordinates can a third charge be placed so that it experiences no net force?

2007-12-17 12:33:40 · 2 answers · asked by Dan 1

1. 105 kg running back runs out of bounds at 8 m/s and collides with a 50 kg cheerleader at rest. If the final velocity of the running back is 5 m/s, what is the magnitude of the resulting velocity of the cheerleader after the collision?

2. A rollercoaster car is coasting at 7 m/s when it collides with 4 rollercoaster cars at rest. They couple after colliding. What is the magnitude of their resulting velocity? Name whether it is going forward or backward as well.

3. Two billiard balls of equal mass are on a billiard table. One ball is set in motion so that it strikes the second ball off center. The second ball travels 53 degrees to the left with a velocity of 6 m/s while the first ball travels 37 degrees to the right with a velocity of 8 m/s. Determine the magnitude of the velocity of the first ball prior to the collision.

The reason I don't know how to do these is because I don't know the equation!!! Thanks!

2007-12-17 12:26:18 · 1 answers · asked by rob f 1

It leaves the track horizontally, striking the ground a distance x = 0.95 m from the end of the track after falling a vertical distance h2 = 1.03 m from the end of the track.
(a) At what height above the ground does the ball start to move?
(b) What is the speed of the ball when it leaves the track?
(c) What is the speed of the ball when it hits the ground?

2007-12-17 12:14:47 · 1 answers · asked by P 1

What is the work done on the car in this time interval?
AND
What is the power delivered by the engine in this time interval?
Can You also show me HOW you got the answer??
Thanks in advance!!!

2007-12-17 12:13:04 · 1 answers · asked by Anonymous

I need some information about Alessandro Volta and how he discovered Methane gas. Nothing else, just the methane gas. and maybe some links to pictures

2007-12-17 12:08:59 · 2 answers · asked by Anonymous

2007-12-17 12:05:16 · 4 answers · asked by JHEIANE 1

Why doesn't this hurt you?

2007-12-17 11:58:05 · 3 answers · asked by JHEIANE 1

A string is wound around a uniform disc of
radius 0.39 m and mass 2.1 kg . The disc is
released from rest with the string vertical and
its top end tied to a fixed support.
The acceleration of gravity is 9.8 m/s^2 .
As the disc descends, calculate the tension
in the string. Answer in units of N. And also Calculate the speed of the center of mass
when, after starting from rest, the center of mass has fallen 1.8 m. Answer in units of
m/s.

2007-12-17 11:56:50 · 2 answers · asked by DC 2

2007-12-17 11:49:44 · 1 answers · asked by Anonymous

A crate containing machine parts sits unrestrained on the back of a flatbed truck traveling along a straight road at a speed of 80 km/hr. The driver applies a constant breaking force and comes to a stop in a distance of 22 m. What is the minimum coefficient of static friction between the crate and the truck bed if the crate is not to slide forward?

2007-12-17 11:16:42 · 1 answers · asked by chewd.pencils 2

Since light has the property of special relativity space and time must distort and dilate respectively to accommodate this. However the effects are only noticeable to humans are speeds approaching light speed.

2007-12-17 10:51:27 · 4 answers · asked by kano7_1985 4

A 2600 kg car traveling north is slowed down uniformly from an initial velocity of 26.7 m/s by a 7950 N braking force acting opposite the car's motion.
What is the car's velocity after 1.92 seconds? Answer in m/s.
help please?

2007-12-17 10:46:12 · 1 answers · asked by Samantha K 1

A small ball 0.51 times as dense as water is dropped from a height of 14m above the surface of a smooth lake. Determine the maximum depth to which the ball sinks. Disregard any energy transferred during impact and sinking. Answer in meters.

2007-12-17 10:36:54 · 1 answers · asked by akanthasy 1

matter which already existed? where did that matter come from? has it always existed? why?

2007-12-17 10:06:55 · 6 answers · asked by Anonymous

maintaining a constant velocity of 10.7 m/s due North relative to the water. The river is 459 m wide.

i already figured that the velocity of the boat is 10.76055761 m/s

but how far downstream has the boat moved by the time is reaches the North shore? answer in meters

2007-12-17 10:05:28 · 1 answers · asked by racecar 1