Question

An astronaut on an alien planet drops a rock into a crater which is 100 meters deep. The rock hits the bottom of the crater 4 seconds later. Is the gravity on this planet stronger or weaker than that of Earth?

Answer 1

The gravity on this planet is stronger than that of earth.

Step-by-step explanation:

First we need to find the acceleration due to gravity value of this planet to compare its gravity force with that of the earth. Hence, we will use second equation of motion:

h = Vi t + (0.5)gt²

where,

h = height or depth of crater = 100 m

Vi = Initial Velocity of rock = 0 m/s

t = time = 4 s

g = acceleration due to gravity on this planet = ?

Therefore,

100 m = (0 m/s)(4 s) + (0.5)(g)(4 s)²

g = (200 m)/(16 s²)

g = 12.5 m/s²

on earth:

ge = 9.8 m/s²

Since,

ge < g

Therefore,

The gravity on this planet is stronger than that of earth.