Launch velocity of the projectile

[Awsom Guy]

Homework Statement

A projectile is launched in such a way as to have a time of flight of 41s and a range of 11 750m.
Calculate:
a) the maximum height reached;
b) the launch velocity of the projectile.

Homework Equations

h=ut-1/2gt^2

The Attempt at a Solution

h=-1/2gt^2
-1/2 * 9.8 * 41^2

I don't get the answer.

 

[ideasrule]

You wrote h=ut-1/2gt^2 but used h=-1/2gt^2, even though u is not 0.

 

[Andrew Mason]

Homework Statement

A projectile is launched in such a way as to have a time of flight of 41s and a range of 11 750m.
Calculate:
a) the maximum height reached;
b) the launch velocity of the projectile.

Homework Equations

h=ut-1/2gt^2

The Attempt at a Solution

h=-1/2gt^2
-1/2 * 9.8 * 41^2

I don't get the answer.

What is the formula for vertical velocity? What is it at maximum height? That will give you the initial vertical velocity. From that, you can use your formula to find maximum height (Hint: what is t at maximum height?).

What is the horizontal velocity?

You can then find the launch velocity (direction and speed) from the horizontal and vertical velocity.

AM