Hello everyone. I've been at this for an hour now, so I think it's about time I asked for help. We have a person on the surface of a planet with an unknown gravitational acceleration. The only measuring instrument available is a very accurate watch. The person is on top of a cliff, and drops a rock from the top of it. It takes 4.15s for the rock to fall from the top of the cliff to the ground below. It travels X meters in total. Afterwards, the person takes the rock, and throws it so that it travels up 2 meters above the top of the cliff, then it falls down to the ground. It travels (4 + X) meters in total Here is a simple depiction: Case 1) || || || \/ Case 2: //\\ || || || || || || || || || \/ This shouldn't be that hard, but I'm still not getting it. Any help would be greatly appreciated. Thank you.