Physics
FlossieDevonish73
2021-04-08 05:28:54
a person does 100 joules of work in pulling back the string of a bow. what will be the initial speed of a 0.5 kg arrow when it is fired from the bow?
ANSWERS
waterskies
2021-04-08 06:06:37

If all the energy she put into bending the bow is completely transmitted to the arrow, then the arrow has the 100 joules of kinetic energy when it leaves the bow.                  Kinetic energy = (1/2) (mass) (speed)²                          100 J        = (1/2) (0.5 kg) (speed²) Divide each side by 0.25 kg:    100 J / 0.25 kg = speed²  [ joule ] = [ newton-meter ] = kg-m²/sec²                                                 100 kg-m²/sec² / 0.25 kg = speed²                                                  400 m²/sec² = speed² Take the square root of each side:     speed = √400 m/s                                                                                 20 m/s                                                                     (about 44.7 mph)                                           

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