Gravity on strange planet and projectile angle for range equal to three times height

[Moneer81]

1. An astronaut on a strange planet finds that she can jump a maximum horizental distance of 30 m if her initial speed is 9m/s. What is the acceleration of gravity on the planet?

2. A projectile is fired in such a way that its horizental range is equal to three times its maximum height. What is the angle of projection?

thanks

 

[arildno]

3. What has Moneer81 done so far?

 

[Moneer81]

by the way this is not a HW I am not in school i am just practicing...

well for the first problem I am wondering if it could be done with the little information we have...

the second one is simpler if we substitute x = 3y into the equations of motion and try to get the x and y component of Vo (initial velocity) then the inverse tangent would give us the angle...

anyone has more detailed comments?

 

[arildno]

1. How is the maximal horizontal distance related to initial speed and acceleration due to gravity?

 

[Moneer81]

well acceleration due to gravity will have an effect on the vertical distance...not the horizental?

 

[arildno]

well acceleration due to gravity will have an effect on the vertical distance...not the horizental?

But when&where the ball hits the ground again depends on the acceleration due to gravity, does it not?

 

[HallsofIvy]

Do you know the formulas for horizontal and vertical motion with a constant (vertical) acceleration?

 

[Moneer81]

yeah yeah you're right...got it :)
i think i was just thinking harder that I had to