ph1 query 21

course Phy 231

4/20 10

021. `query 21

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Question: `q Explain how to obtain the final speed and direction of motion of a projectile which starts with known velocity in the horizontal direction and falls a known vertical distance, using the analysis of vertical and horizontal motion and vectors.

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Your solution:

This means that we know what the initial velocity, displacement, and acceleration in the vertical distance. We can then easily find the final velocity by implementing the equation: vf^2 = v0^2 + 2 * a * ds. For the horizontal distance we have the final velocity. We can then use what we have to find the magnitude and distance with vectors.

The magnitude is: sqrt(horizontal velocity^2 + vertical velocity^2).

The distance is: tan-1(vertical velocity / horizontal velocity).

confidence rating #$&*

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Given Solution:

`a** The horizontal velocity is unchanging so the horizontal component is always equal to the known initial horizontal velocity.

The vertical velocity starts at 0, with acceleration thru a known distance at 9.8 m/s^2 downward. The final vertical velocity is easily found using the fourth equation of motion.

We therefore know the x (horizontal) and y (vertical) components of the velocity. Using the Pythagorean Theorem andarctan (vy / vx) we find the speed and direction of the motion. **

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Self-critique (if necessary):ok

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Self-critique rating #$&*3

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Question: `qGive at least three examples of vector quantities for which we might wish to find the components from magnitude and direction. Explain the meaning of the magnitude and the direction of each, and explain the meaning of the vector components.

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Your solution:

a basketball being thrown into a hoop, where the player is standing, the angle at which it gets thrown in.

a person parachuting off of a cliff, the angle at which he ends up landing, how far he goes.

two boats moving at different speeds in different directions, the distance they travel and the angle at which they leave the main port they both depart from.

confidence rating #$&*

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Given Solution:

`a** GOOD STUDENT RESPONSE:

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Self-critique (if necessary):

I am not too sure if the answers that I give are similar to what you are looking for.

Your examples are very good.

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Self-critique rating #$&*

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Question: `qExamples might include:

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Your solution:

confidence rating #$&*

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Given Solution:

`aA force acting on an object causing it to move in an angular direction.

A ball falling to the ground with a certain velocity and angle.

A two car collision; velocity and momentum are both vector quantities and both important for analyzing the collision..

The magnitude and directiohn of the relsultant is the velocity and direction of travel.

The vector components are the horizontal and vertical components that would produce the same effect as the resultant.

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Self-critique (if necessary):

I think my answers were along the lines of what you were looking for.

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Self-critique rating #$&*3

&#Good work. See my notes and let me know if you have questions. &#