# Throwing a frisbee and measuring change in mechanical energy

1. Nov 10, 2012

### sjcorona

A 75g Frisbee I thrown from a point 1.1 m above the ground with a speed 12 m/s when it has reached a height \$.1 m its speed is 10.5 m/s What is the reduction in Emec of the frisbee-earth system because of air drag?

At first I thought Since ΔEmec= Δk+Δu the change is -0.61 J
Then I reasoned that only the kinetic is affected by drag Δk= -1.3 J
Now I'm wondering if I need to split the velocity into x and y components so I can separate the decrease due to gravity and the decrease due to drag? But I don't thinknthats what they want me to do. According to the guide The answer ends up being 0.53 J

2. Nov 10, 2012

### Staff: Mentor

Calculate the total mechanical energy at each point.

3. Nov 10, 2012

### sjcorona

I did that too,Emec2 - Emec1 is still 0.61

4. Nov 10, 2012

### Staff: Mentor

I don't see how you got that answer (or the guide's answer). What is the final height of the frisbee? Is it 0.1 m?