Physics help...again?
Fleas have remarkable jumping ability. A 0.40 mg flea, jumping straight up, would reach a height of 40 cm if there were no air resistance. In reality, air resistance limits the height to 20 cm .
What is the flea's kinetic energy as it leaves the ground?
At its highest point, what fraction of the initial kinetic energy has been converted to potential energy?
I kept getting the answer for a as .001568, but it is wrong, how do i solve it?
Answers
Anonymous
Kinetic Energy when flea leaves the ground is converted to Potential Energy due to height (mgh) KE =mgh KE=0.4 x 9.81 x .4 What is the flea's kinetic energy as it leaves the ground? KE= 1.57 J However, because of air resistance some of this energy gets used up and what remains only allows the flea to reach a height of 0.2m. At its highest point, what fraction of the initial kinetic energy has been converted to potential energy? KE = 0.4 x 9.81 x 0.2/ 0.4x 9.81 x 0.4 = 0.2/0.4 = 0.5 Only half of the original FE of 1.57 J was used to reach the max height of 0.2 m Ans : 0.5
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