The plan was characterized by certain properties: it is always mutually perpendicular segment that connects the end of the directed points on the surface of the body segment that connects these points. The length of the segments that join the end of the velocity vectors of certain points of the body, is proportional to the length of segments that join corresponding to these vectors point.
The more the scale of the plan, in which the vectors V, the more accurate will the answer to the problem being solved, respectively, at the smaller scale obtained during the measurement and subsequent calculation, the answer will be approximate.
How to build a geometric plane, it is easiest to explain on specific example, as the building and further calculation in each case is different. Overall, the construction of such a plan need to know at least a speed of at least one of the points of a shape or mechanism, and the direction of the velocity vector of any other point of the plot.
Let ABC, there is a mechanism, consisting of rods connected by hinges. Let the speed of t is known and equal to 2 m/s, and V is a perpendicular bisector to the segment HS and the vector B is perpendicular to AB. You want to find the speed of the T. B.
The random point put the pole mechanism - so On, and then select the desired scale. Further, the vector V t need to move to the beginning of this vector coincides with T. O, and need to move it in parallel. Draw a straight OD that will start from the pole and is perpendicular to the line BA.
From the end of the vector V T. To draw a straight line, which is perpendicular to BV. A direct cross another OD. The point at which the data straight intersect, determine how used.
From the resulting cut On and calculate the speed, etc B: to do this, accurately measure the length of line About, and then multiply its length with the scale of the drawing in relation to the real body or parts - get the speed module of T. B
Advice 2 : How to build a plan accelerations
The construction plan acceleration is one of the solutions to the problems of the status of links of the mechanism. For such constructs must be defined kinematic diagram of the mechanism and function of its initial displacement (initial mechanism with one degree of freedom) units.
In the selected scale build the kinematic scheme. Then to the drawing, and apply a fixed axis, and links, which are defined. This assumes that the initial link is moving with a constant speed. The provisions of the other parts build on the known size relative to the previously defined links.
Further, the position of the outer links of the kinematic pairs of the mechanism vector equations describe the velocity and acceleration. To do this, use the technique of decomposing their motion into translational and rotational. Acceleration of any link of the mechanism is geometrically the sum of the acceleration of the other level is taken as pole, and acceleration, which is the first link gets around the rotation pole.
While solving the problem of the mechanism represented in the position for which you want to determine the acceleration of the desired link. First of all, according to the tasks determine the level (point), taken as a pole.
Then in the space near the kinematic scheme of the mechanism of the point - pole accelerate, the beginning of all vectors of total accelerations. Then set the scale of the building, define a fixed axis, directions.
Then build the vectors, the acceleration of which is known (typically vectors of the initial level). Next, make a vector equation for the unknown accelerations. In the solution of equations determine the unknown magnitude and direction, and then these solutions apply to the plan. If the unknown value of the acceleration, then the plan is applied to a video describing the direction of the acceleration vector.
When solving vector equations, find the value of acceleration, and the scale put the value obtained previously for direct. Next, make a vector equation for the next link of the mechanism, their velocity and acceleration determine proportions in accordance with the properties of plans, speeds and accelerations.
This method is a graphical solution of the problem of the position of the mechanism links is undoubtedly striking, but not entirely accurate.