posted by Fel .
an anchor shoots an arrow into a piece of wood. the arrow is traveling at 120 km/h when it strikes the wood. the arrow penetrates 3.8 cm into the wood before stopping. what is the average acceleration (in m/s^2) into the wood?
first convert 120 km/hr into m/s
120 km/hr(1000 m/km)(1 hr /3600 s) = 33.3 m/s
It drops from 120 to zero so during the stop it averaged 33.3/2 m/s = 16.65 /s SPEED
it went .038 meters at average speed of 16.65 so it took .038 m /16.65 m/s = .00228 seconds to stop.
so change in speed/change in time = (0 - 33.3) / .00228
= -14605 m/s^2