Projectile Motion Homework: Finding Time, Distance, and Speed

[deaninator]

Homework Statement

A rock is thrown horizontally from a bridge at a speed of 32.6 m/s. If the rock is 32.0 meters above the river at the moment of release, find how long the rock is in the air? 2.56 seconds. Find the horizontal distance to the point of impact from the point of release? 83.31 meters
Find the speed with which the rock strikes the river? I don't know

Homework Equations

V=Sq root of(vx^2 + vy^2)
Vox = Vx
X=VoxT

Vy=Voy + at
y=voyt + 1/2at^2
Vy^2 = Voy^2 + 2ay

The Attempt at a Solution

MY HINT:Apparently this is a vector problem. "Add" horizontal and vertical velocities. So i added the horizontal velocity that was 32.6...but what's the vertical velocity?

 

[fss]

v_x and v_y are independent of each other. Considering only the y-direction, what can you say about the initial speed of the ball in that direction?

 

[deaninator]

v_x and v_y are independent of each other. Considering only the y-direction, what can you say about the initial speed of the ball in that direction?

Ok vertical velocity is 32.6 m/s...but how do i find the horizontal speed?

 

[fss]

Ok vertical velocity is 32.6 m/s...but how do i find the horizontal speed?

It's already given, neglecting air resistance. The speed at which the rock hits the ground will be the resultant vector of v_x and v_y.

 

[deaninator]

It's already given, neglecting air resistance. The speed at which the rock hits the ground will be the resultant vector of v_x and v_y.

If it is already given then what is it? Oh is it 12.5 m/s?

 

[fss]

Homework Statement

A rock is thrown horizontally from a bridge at a speed of 32.6 m/s.

There you go.