mastering chem problem 10.56 Fleas have remarkable jumping ability. A 0.50mg fle

Question

mastering chem problem 10.56

Fleas have remarkable jumping ability. A 0.50mg flea, jumping straight up, would reach a height of 35cm if there were no air resistance. In reality, air resistance limits the height to 20cm .

Part A

What is the flea's kinetic energy as it leaves the ground?

Express your answer to two significant figures and include the appropriate units.

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Part B

At its highest point, what fraction of the initial kinetic energy has been converted to potential energy?

Express your answer using two significant figures.

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Explanation / Answer

(a) K.E = mV^2 / 2 (neglect air resistance - that takes effect after it leaves the ground)

it is ALSO simply mgh = 0.0000005 x 9.81 x 0.4

this is true equally for an object fired directly upward OR dropped

0.0000005 kg
g = 9.81
h = 0.4 m

= 0.000001962 joules ...or almost 2 micro joules

(b) at it's highest point (20cm) HALF the kinetic energy has been converted to potential energy of height. The rest has been dissipated as air resistance (creating turbulence in the air surrounding it)

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