an archer shoots an arrow into a piece of wood. the arrow is traveling at 120km/h when it strikes the wood. the arrow penetrates 3.8cm into the wood before stopping. what is its average acceleration (in m/s squared) into the wood?

Answer 1

You need an equation of motion

v^2 = u^2 + 2aS

v = final velocity
u = initial velocity
a = acceleration
s = displacement

Watch your units. The velocity is in km/h and your displacement is in cm and you want the answer in m/s^2