course phy121 EΨgcסּ͎Ϥassignment #019
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11:58:04 Query class notes #20 Explain how we calculate the components of a vector given its magnitude and its angle with the positive x axis.
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RESPONSE --> The x componet of the vector is the: magnatude * cos(theta) The y component is: magnatude * sin(theta) confidence assessment: 3
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11:58:27 ** STUDENT RESPONSE: x component of the vector = magnitude * cos of the angle y component of the vector = magnitude * sin of the angle To get the magnitude and angle from components: angle = arctan( y component / x component ); if the x component is less than 0 than we add 180 deg to the solution To get the magnitude we take the `sqrt of ( x component^2 + y component^2) **
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RESPONSE --> self critique assessment:
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12:01:13 Explain what we mean when we say that the effect of a force is completely equivalent to the effect of two forces equal to its components.
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RESPONSE --> It means that if you have a force of 5.66N at an angle of 45*, it is equivilant to two forces of 4N, one at 0* or along the positive x-axis and one of 4N at 90* or along the positive y-axis. confidence assessment: 3
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12:01:25 ** If one person pulls with the given force F in the given direction the effect is identical to what would happen if two people pulled, one in the x direction with force Fx and the other in the y direction with force Fy. **
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RESPONSE --> self critique assessment: 3
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12:03:37 Explain how we can calculate the magnitude and direction of the velocity of a projectile at a given point.
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RESPONSE --> The point is the location of the end of the line segment on a coordinate system. the magnatude of the vector is: sqrt(x^2 + y^2) The angle of direction of the vector is: tan-1(y/x) If x<0, and y>0, you add 180* If x>0 and y<0, then you add 360* confidence assessment: 3
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12:03:43 ** Using initial conditions and the equations of motion we can determine the x and y velocities vx and vy at a given point, using the usual procedures for projectiles. The magnitude of the velocity is sqrt(vx^2 + vy^2) and the angle with the pos x axis is arctan(vy / vx), plus 180 deg if x is negative. **
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RESPONSE --> self critique assessment: 3
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12:04:51 Explain how we can calculate the initial velocities of a projectile in the horizontal and vertical directions given the magnitude and direction of the initial velocity.
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RESPONSE --> you simply use the cos/sin equasions from before: x = magnitude * cos(direction) y = magnitude * sin(direction) confidence assessment: 3
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12:04:57 ** Initial vel in the x direction is v cos(theta), where v and theta are the magnitude and the angle with respect to the positive x axis. Initial vel in the y direction is v sin(theta). **
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RESPONSE --> self critique assessment: 3
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