[Mode1]

Here is the problem:

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

I am having trouble with this because there is no time given as to how long it took to go 3.8cm. Am I wrong thinking this way? Can it be solved with just the above info?
Would you please help me solve this? Thanks.

[Capuchin]

well you know that between 0cm and 3.8cm, it slows from 120km/h to a stop.

look at your suvat equations for an equation with does not have time as a variable, use it and you should get the answer you're looking for.

[jiten55]

u = initial velocity = 33.33 m/per sec

v = final velocity = 0, s = distance = 3.8cm = .038 m, a = acceleration = ?

v^2 - u^2 = 2as

- 33.33^2 = 2a (.038)

a = -14620 (meter, sec)

[Capuchin]

u = initial velocity = 33.33 m/per sec

v = final velocity = 0, s = distance = 3.8cm = .038 m, a = acceleration = ?

v^2 - u^2 = 2as

- 33.33^2 = 2a (.038)

a = -14620 (meter, sec)

I don't think this was necessary, the OP just needed a poke in the right direction. I think we have a responsibility to help people learn, not just give them answers.