Gravity decreases your kinetic energy when you are driving uphill since the direction of motion is opposite for both. Driving uphill is force going upward while gravity pulls object down. When it is going downhill, the car tends to go faster since the gravity helps the object to go down by adding another value to the total acceleration of the motion of the object. Using the forces of balance, an object going up tends to become heavier while object going down tends to become lighter because of the gravity factor. Another analogy is the motion of elevators going up and down that incurs effects to your weiight.
Answer:

Explanation:
As we know that initial speed of the fall of the stone is ZERO

also the acceleration due to gravity on Mars is g
so we have

now we have

now if the same is dropped for 4t seconds of time
then again we will use above equation


