Asked Dec 8, 2019
A 68.1 kg runner has a speed of 3.50 m/s at one instant during a long-distance event.
 For (a) Apply the definition of kinetic energy. For (b) use the work-energy theorem.
What is the runner's kinetic energy at this instant (in J)?
How much net work (in J) is required to triple her speed?

Expert Answer

Step 1

(a) The runner’s kinetic energy at the instant is


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KE, = -m Новлья16.50а/5 2 (68.1kg)(3.50m/s)* = 417.1J

Step 2

(b) The kinetic energy required...


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(1/2)nn KE, (1/2)m(3v) KE, KE, = 9KE, = 9(417.1J) = 3753.9J


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