If a stone with an original velocity of 0 is falling from a ledge and takes 8 seconds to hit the ground, what is the final velocity of the stone?

Using v = u + at
u = 0m/s
t = 8 sec
a = 10m/s^2
therefore, final velocity, v = 0+ 8*10
v= 80m/s

To answer this question, we will use the equation of motion:
V = u + at where:
V is the final velocity that we need to calculate
u is the initial velocity of the stone = 0 m/sec
a is the acceleration due to gravity = 9.8 m/sec^2
t is the time taken by the stone to hit the ground = 8 seconds

Substitute with the givens in the above equation to get the final velocity of the stone as follows:
V = 0 + 9.8(8) = 78.4 m/sec 

A. to determine if humans can explore mars safely

This is what a calorimeter is used for simpler ex, to measure calories in food.