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This text is meant to accompany class discussions. It is not everything there is to know about uniform circular motion. It is meant as a prep for class. More detailed notes and examples are given in the class notes, presentations, and demonstrations (click here.) 

Determining Direction for Motion in a Plane 
In order to determine the direction, you need to know right triangle trigonometry.
Do the review if its been a while since you have used sine, cosine, and tangent.

To find the direction of a projectile, use kinematics to find the vertical velocity, Vx, and the horizontal velocity, Vx, at a position along the path. Use these two components to create a triangle. Then use trigonometry to calucalate the direction. 

Example 1 

A ball is thrown off the top of a cliff with an initial vertical velocity if 4.00 m/s upwards and with a horizontal velocity of 6.00 m/s. Neglect air resistance. Vertically the ball experiences the acceleration due to gravity. Horizontally the ball is moving at a constant velocity. What is the direction and speed of the ball after 4.00 seconds? 

Solution 


Example 2 

A ball is thrown off the top of a cliff with an initial vertical velocity if 4.00 m/s upwards and with a horizontal velocity of 6.00 m/s. Neglect air resistance. Vertically the ball experiences the acceleration due to gravity. Horizontally the ball is moving at a constant velocity. After some unknown number of seconds the ball is 62.4m below the starting point and 24 m to the right. What is the ball's direction and speed? 

Solution 






