I don't get this question help me please?

[jojo14]

An astronaut on a newly discovered planet wants to determine the acceleration due to gravity. In his experiment, he fires a small cannon from the edge of a mesa that is 125m high. The initial horizontal velocity of the cannon ball is 64m/s. The projectile travels 261m horizontally before it strikes the surface of the planet. After determining the acceleration due to gravity, what might the astronaut conclude about this planet?

answer: Ag=15.03m/s^2

i don't get it at all, help please,

and thanks!

 

[thaer_dude]

You have the initial horizontal velocity, and the distance traveled horizontally. Using your equations, you should be able to find the time it takes for the ball to hit the ground.

You have all the information you need now. For the vertical "part" of this problem, you know what distance must be traveled vertically before the ball hits the ground, you know the initial vertical velocity and you know the time it takes for the ball to hit the ground. Using your equations, you can then solve for the acceleration due to gravity.