Query 21

#$&*

course Phy 231

8/1/11

If your solution to stated problem does not match the given solution, you should self-critique per instructions at

http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/lev

l1_22/levl2_81/file3_259.htm.

Your solution, attempt at solution. If you are unable to attempt

a solution, give a phrase-by-phrase interpretation of the problem

along with a statement of what you do or do not understand about

it. This response should be given, based on the work you did in

completing the assignment, before you look at the given solution.

If your solution to stated problem does not match the given

solution, you should self-critique per instructions at

http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/lev

l1_22/levl2_81/file3_259.htm.

Your solution, attempt at solution. If you are unable to attempt

a solution, give a phrase-by-phrase interpretation of the problem

along with a statement of what you do or do not understand about

it. This response should be given, based on the work you did in

completing the assignment, before you look at the given solution.

021. `query 21

*********************************************

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.

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

First you can use y-y0 = (v0 * sin(theta))t - 0.5gt^2 to find t.

then you can use vf = v0 +at to find vf. next you find the

resultant by R = sqrt(vf^2 + v0^2). For the direction you use

tan^-1(vf/v0). If y is negative then add 360 to ans. If x is

negative then add 180 to ans.This will give you an angle that is

taken from the positive x-axis.

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

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 and arctan (vy /

vx) we find the speed and direction of the motion. **

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary): OK

------------------------------------------------

Self-critique Rating: 3

*********************************************

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.

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

A projectile moving with the wind blowing across it.

Ojects colliding into one antoher.

The forces acting on an objcet sliding down a ramp.

Magnitise would give you the velocity or the net force. The

direction would give you the angle at which the vector is

pointing. The components are the x and y components that also

give you the resultant or magnitude.

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a

Examples might include:

A 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.

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary): OK

------------------------------------------------

Self-critique Rating: 3

"

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:

"

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:

#*&!

&#This looks good. Let me know if you have any questions. &#