# Euquations of kinematics in two dimensions

1. Sep 28, 2009

### pookisantoki

A golfer imparts a speed fo 26.0m/s to a ball, and it travels the maximum possible distance before landing on the green. The tee and the green are at the same elevation. A.) How much time does the ball spend in the air? B.) What is the longest "Hole in one" that the golfer can make, if the ball does not roll when it hits the green.

a.) Acceleration of Y= -9.80 Voy=?? and Vy=26m/s and were trying to figure out the T. Since I'm missing Voy and I dont have Vox I can't figure Voy out and I dont know what formula to use not having having Time or Voy.

b.) I know the problem is looking for "Y" displacement but since i can't figure out part A i can't really figure out part b.

2. Sep 28, 2009

### Delphi51

Your best bet for these 2D projectile questions is to always write two headings and the appropriate formulas for the type of motion involved:
HORIZONTAL
d = vt

VERTICAL
V = Vi + at, d = Vi*t + .5*a*t^2

In this case it is difficult to separate the 26 m/s into its horizontal and vertical components unless you know the angle that gives the "maximum possible distance". Usually in physics courses, you get to try shooting the ball and many different angles to discover the best angle. If you haven't done that yet, you could do it with this problem.

3. Sep 28, 2009

### pookisantoki

In this case it is difficult to separate the 26 m/s into its horizontal and vertical components unless you know the angle that gives the "maximum possible distance". Usually in physics courses, you get to try shooting the ball and many different angles to discover the best angle. If you haven't done that yet, you could do it with this problem.

I'm not sure how you would find the best angle??

4. Sep 28, 2009

### Delphi51

Try 30 degrees and calculate how far it goes. Then try 35, 40, 45, 50 and so on. You should see a maximum. When you do, try going a degree at a time to pin it down. It is worth making a spreadsheet to automate the process. Of course you could ask someone for the answer, but it is really good to figure it out yourself. If you are handy with algebra, you can carry through the calculation with a variable angle A and get a function for the distance. Graph the function vs A to see where the maximum is. Or use calculus to get the maximum if you know that.