Find speed given mass, force, and distance

[nPwn]

1. An 88-g arrow is fired from a bow whose string exerts an average force of 110 N on the arrow over a distance of 78 cm. What is the speed of the arrow as it leaves the bow?
2. I'm completely lost, sorry!

 

[dannyR]

You know the force and mass of the arrow, so you can calculate the acceleration:

F=ma

then using equations of motion for constant acceleration, meaning the force providing the acceleration doesn't change throughout the motion.

v^2 = u^2 +2as,
v=final velocity, u = intial velocity=0, a=(f/m), s is distance over which the object is accelerated.

ill check your answers once you have applied yourself :).

 

[Nugatory]

DannyR's answer is right, but it's not the only possible way of solving the problem.

You could also use W=Fd to calculate the kinetic energy of the arrow, use the formula for kinetic energy as a function of velocity to get the speed. An easy way to check your work is to see if you get the same answer both ways.