Percentage of Block Energy Dissipated

[Masrat_A]

Homework Statement

During a vertical fall, a block's speed increases from 6 m/s to 8m/s over a 3 m distance. What percentage of the block's energy is dissipated due to air resistance over this distance?

Homework Equations

$E_f = E_i$

The Attempt at a Solution

$E_f = DE_i$
$KE_f + PE_f = D(KE_i + PE_i)$
$1/2MV_f^2 + 0 = D(1/2MV_i^2 + Mgy)$
$V_f^2 = D(V_i^2 + 2gy)$
$64 = D(36 + 60)$
$D = 0.67$

$1 - 0.67 = 0.33$
$0.33 * 100 = 33$

I wasn't so sure on what to label dissipated energy, so I went with D. Does any of this seem reasonable?

 

[kuruman]

It's all very reasonable.