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Projectile MotionAn example of curved motion with the constant acceleration is the projectile motion. This is the two-dimensional motion of a particle thrown obliquely into the air. If we choose a reference frame with the positive y-axis vertically upward, we may put
Let us further choose the origin of our reference frame to be the point at which the projectile begins its flight Figure 3.2
The velocity at t = 0, the instant the projectile begins its flight, is
The horizontal velocity component retains its initial value throughout the flight, so that
The vertical component of the velocity will change with the same in accordance with vertical motion with the constant downward acceleration
so that
The magnitude of the resultant velocity vector at any instant is
The angle
The x-coordinate of the particle’s position at any time is
The y-coordinate is
Let us suppose that we know the change of acceleration with time, i.e., the function
then the velocity of the particle at the instant t may be easily found
The less
If the body moves with variable acceleration the path covered by it is defined in the same way.
Fig. 3.3 gives a graphical explanation of this calculation. This path is represented by the area Figure 3.3
Date: 2015-01-12; view: 1237
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