Change in the acceleration of Gravity given resistance

[jackthompson]

Hello,

This is the first time i have posted here and could really use some help, my class was given this question as enrichment after a free fall test and i would like to learn how to do it. i have checked my textbook but could not find any way to calculate the change in the acceleration of gravity given the resistance.

Homework Statement

a 50kg block is submerged in an unknown substance,the block is then dropped 10m to the bottom of the substance. if the substance provides a resistance of 300 N, how long does it take the block to reach the bottom? (Gravity = 9.81m/s^2)

Homework Equations

This is what i need help with.

The Attempt at a Solution

I sketched out the quesiton, but like i said i could not find any equations for this type of question.

 

[PhanthomJay]

Are you familiar with free body diagrams showing the forces acting on the block, and Newton's laws, and the kinematic motion equations? Please show an attempt.