course Phy 201 ??????n????·?K?assignment #019
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22:52:08 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 --> Vx = magnitude * cos(theta) vy = magnitude * sin(theta) confidence assessment: 2
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22:52:20 ** 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 --> ok self critique assessment: 3
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23:26:44 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 --> If the components are the same, the force will be the same. confidence assessment: 2
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23:26:56 ** 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 --> ok self critique assessment: 3
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23:39:47 Explain how we can calculate the magnitude and direction of the velocity of a projectile at a given point.
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RESPONSE --> magnitude = sqrt (x^2 + y^2) direction = If x and y are pos, the angle is arctan( y / x ) If x is negative, the angle is arctan( y/ x ) + 180 deg. If x is positive and y negative, arctan( y / x) +360 confidence assessment: 2
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23:40:00 ** 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 --> ok self critique assessment: 3
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00:18:03 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 --> make a graph and draw out the x and y components confidence assessment: 0
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00:19:40 ** 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 --> ok. why is this the initial velocity as opposed to the average velocity? self critique assessment: 2
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