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Sudoku 4 Not so easy??. But 2222simple 4 goiitans??

2				1	8
	1	5	3		2			8
		8		9				3
		4	1		5		9
5								2
	3		7		6	8
9				7		6
6			8		1	2	3
			9	6				1

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Momentum

The sports announcer says "Going into the all-star break, the Chicago White Sox have the momentum." The headlines declare "Chicago Bulls Gaining Momentum." The coach pumps up his team at half-time, saying "You have the momentum; the critical need is that you use that momentum and bury them in this third quarter."

Momentum is a commonly used term in sports. A team that has the momentum is on the move and is going to take some effort to stop. A team that has a lot of momentum is really on the move and is going to be hard to stop. Momentum is a physics term; it refers to the quantity of motion that an object has. A sports team which is "on the move" has the momentum. If an object is in motion ("on the move") then it has momentum.

Momentum can be defined as "mass in motion." All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion. The amount of momentum which an object has is dependent upon two variables: how much stuff is moving and how fast the stuff is moving. Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object.Momentum = mass * velocity

In physics, the symbol for the quantity momentum is the small case "p"; thus, the above equation can be rewritten as p = m * v

where m = mass and v=velocity. The equation illustrates that momentum is directly proportional to an object's mass and directly proportional to the object's velocity.

The units for momentum would be mass units times velocity units. The standard metric unit of momentum is the kg*m/s. While the kg*m/s is the standard metric unit of momentum, there are a variety of other units which are acceptable (though not conventional) units of momentum; examples include kg*mi/hr, kg*km/hr, and g*cm/s. In each of these examples, a mass unit is multiplied by a velocity unit to provide a momentum unit. This is consistent with the equation for momentum.

Momentum is a vector quantity. As discussed in an earlier unit, a vector quantity is a quantity

which is fully described by both magnitude and direction. To fully describe the momentum of a 5-kg bowling ball moving westward at 2 m/s, you must include information about both the magnitude and the direction of the bowling ball. It is not enough to say that the ball has 10 kg*m/s of momentum; the momentum of the ball is not fully described until information about its direction is given. The direction of the momentum vector is the same as the direction of the velocity of the ball. In a previous unit, it was said that the direction of the velocity vector is the same as the direction which an object is moving. If the bowling ball is moving westward, then its momentum can be fully described by saying that it is 10 kg*m/s, westward. As a vector quantity, the momentum of an object is fully described by both magnitude and direction.

From the definition of momentum, it becomes obvious that an object has a large momentum if either its mass or its velocity is large. Both variables are of equal importance in determining the momentum of an object. Consider a Mack truck and a roller skate moving down the street at the same speed. The considerably greater mass of the Mack truck gives it a considerably greater momentum. Yet if the Mack truck were at rest, then the momentum of the least massive roller skate would be the greatest; for the momentum of any object which is at rest is 0. Objects at rest do not have momentum - they do not have any "mass in motion." Both variables - mass and velocity - are important in comparing the momentum of two objects.

If U happen 2 fall don't lie there & die

Secret of Success

During Karate competitions held in Gujarat, a young man won a gold medal. Surprisingly, his left leg is affected by polio.What is more astonishing, the competition was not for disabled men.It was an open competition.When a reporter asked him the secret behind his success, he said smilingly:

"I received the opponent's punches on my left leg that is paralyzed and so does not give pain.Before he could strike again I rained blow after blow on him with my fists and defeated him."At this, tears trickled down from the journalist's eyes.

hi

plz send it

jyothisusangeorge@rediff.com

Rolling friction is caused primarily by the interference of small indentations formed as one surface rolls over another. This is the idea behind the frictional forces involved with wheels, cylinders, and spheres. In the ideal case of the wheel, we must first look at the forces acting on the wheel. In pure rolling motion friction is required to start, stop, change the motion of a wheel. Below we can see the frictional force necessary to begin motion, and get the wheel moving at a velocity v. In pure rolling motion, friction causes the wheel to catch and stops the sliding and slipping motion; for example when a car spins its tires, slipping is taking place, thus the frictional force works to stop the spinning out and causes the tires to catch and begin pure rolling motion.

The frictional force, f, the force required to slow the wheel produces a torque which tends to decrease the angular velocity, w. (The normal and gravitational forces produce no effect because their line of action is through the center of rotation.) However, the surface could not possibly have such an effect on the wheel once the wheel has achieved pure rolling motion and constant angular and linear velocity. Zero friction occurs only for horizontal motion at constant velocity, but it is non-zero for any case in which acceleration is occurring parallel to the direction of motion of the center of mass, as when the object is rolling-without-slipping up or down a sloped surface. If we consider the rotation as being about the center of mass of the object, then the frictional force must be in a direction to provide the torque necessary to decrease or increase the angular velocity, depending on whether the object is accelerating or decelerating, respectively. Note that the friction can be in the direction of motion (rolling downhill) or opposite to it (rolling uphill). In pure rolling motion there is no sliding or slipping, thus the contact points have no relative motion (no relative velocity). This results in a frictional force of zero. Therefore, the wheel will roll forward with constant velocity, v = Rw, where R is the radius of the wheel.

In the actual case of the rolling wheel, the free-body diagram is much different. Both the wheel and the surface will undergo deformations due to their particular elastic characteristics. At the contact points, the wheel flattens out while a small trench is formed in the surface. The normal force is now distributed over the actual contact area rather than the point just below the center of the wheel.

Furthermore, the wheel takes on a sort of plowing motion resulting in increased deformation at the front of the wheel, while the rear of the wheel undergoes little deformation which results in the majority of the normal force being located at the front. When the wheel and the surface deform there is a minute amount of slipping, but the majority of the force is due to static friction. The overall rolling friction results in a force at the center of the wheel and is parallel to the surface of contact, and is represented by the equation:

This resultant frictional force is still rearward acting (tending to contribute to the angular velocity), but the new distribution of the normal forces creates a net torque negating the rotational contribution of the friction and causing an overall deceleration of the wheel?s forward velocity. Also, the major source of energy losses during rolling motion is primarily due to the deformation that occurs when the two surfaces are compressed and relaxed. This continual process generates heat in both the wheel and the surface.

Sudoku 3 Not so easy??. But 2222simple 4 goiitans??

8

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9

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8

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2

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1

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9

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1

8

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josusangeorge@yahoo.co.in

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                            A BIG SALUTE

                                WAITING 4 U

Sudoku 2 Not so easy??. But 2222simple 4 goiitans??

1

6

3

2

8

1

5

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9

9

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Momentum

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