Question

How to solve this problem?

Answer 1

5.6 m/s

Step-by-step explanation:

m = 0.25 kg, h = 2 m

initail energy = mgh = 0.25 * 9.81 * 2 = 4.91 J

80% of 4.91 J converted to final kinetic energy mv^2/2

so 0.8 * 4.91 = 0.25*v^2/2

v^2 = 2*0.8*4.91/0.25 = 31.4

v = 5.6 m/s