A rock is dropped off a cliff with zero initial velocity and strikes the ground with 30 m/s.How high was the cliff?

Tall enough to get hurt if you fall off it.


This is your homework assignment, show us your work and what you think the answer is. We won't do your assignment so you don't have to.

You must first understand that an object falls roughly 32 ft/sec/sec. In your case, since you are using metric , you will have to convert a few things and take into account air resistance. F_tot = F_grav + F_air = mg - ks(t)

Since you are a beginning physics student I will give you a big hint: you need to memorize and learn to use the basic equations of motion that involve time, distance, velocity, and acceleration. You should recognize this one:



Here the value to use for acceleration is 'g',' which is -9.8 m/s^2, and the initial velocity is zero. Now solve for 'd' - what do you get?