What does ccw stand for in physics

The first child has a mass of Both conditions for equilibrium must be satisfied. In part a , we are asked for a distance; thus, the second condition regarding torques must be used, since the first regarding only forces has no distances in it.

To apply the second condition for equilibrium, we first identify the system of interest to be the seesaw plus the two children. We take the supporting pivot to be the point about which the torques are calculated. We then identify all external forces acting on the system. The three external forces acting on the system are the weights of the two children and the supporting force of the pivot.

Let us examine the torque produced by each. Torque is defined to be. The torques exerted by the three forces are first,. Note that a minus sign has been inserted into the second equation because this torque is clockwise and is therefore negative by convention.

Since F p acts directly on the pivot point, the distance r p is zero. A force acting on the pivot cannot cause a rotation, just as pushing directly on the hinges of a door will not cause it to rotate. Now, the second condition for equilibrium is that the sum of the torques on both children is zero. Weight is mass times the acceleration due to gravity.

Entering mg for w , we get. As expected, the heavier child must sit closer to the pivot 1. This part asks for a force F p. The easiest way to find it is to use the first condition for equilibrium, which is. The forces are all vertical, so that we are dealing with a one-dimensional problem along the vertical axis; hence, the condition can be written as. Choosing upward to be the positive direction, and using plus and minus signs to indicate the directions of the forces, we see that.

The two results make intuitive sense. The heavier child sits closer to the pivot. The pivot supports the weight of the two children. Several aspects of the preceding example have broad implications. First, the choice of the pivot as the point around which torques are calculated simplified the problem. Since F p is exerted on the pivot point, its lever arm is zero.

Hence, the torque exerted by the supporting force F p is zero relative to that pivot point. The second condition for equilibrium holds for any choice of pivot point, and so we choose the pivot point to simplify the solution of the problem. Second, the acceleration due to gravity canceled in this problem, and we were left with a ratio of masses. This will not always be the case. Always enter the correct forces—do not jump ahead to enter some ratio of masses.

Third, the weight of each child is distributed over an area of the seesaw, yet we treated the weights as if each force were exerted at a single point. This is not an approximation—the distances r 1 and r 2 are the distances to points directly below the center of gravity of each child. As we shall see in the next section, the mass and weight of a system can act as if they are located at a single point.

Finally, note that the concept of torque has an importance beyond static equilibrium. Torque plays the same role in rotational motion that force plays in linear motion. We will examine this in the next chapter. By convention, counterclockwise torques are positive, and clockwise torques are negative. Conceptual Questions 1. What three factors affect the torque created by a force relative to a specific pivot point? For such cases as this, it is important that there be some convention for describing the direction of such a vector.

The convention upon which we can all agree is sometimes referred to as the CCW convention - counterclockwise convention. Using this convention, we can describe the direction of any vector in terms of its counterclockwise angle of rotation from due east. The direction north would be at 90 degrees since a vector pointing east would have to be rotated 90 degrees in the counterclockwise direction in order to point north. The direction of west would be at degrees since a vector pointing west would have to be rotated degrees in the counterclockwise direction in order to point west.

Further illustrations of the use of this convention are depicted by the animation below. Economics and finance. Education and pediatrics. Engineering and technology. English grammar and anthology. Fashion and show business.

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