Multnomah falls in Oregon are approximately 206m high. If the Columbia river is flowing horizontally at 2.90m/s just before going over the falls, what is the overall velocity of the water when it hits the bottom?

Respuesta :

Answer:

63.6 m/s

Explanation:

The motion of the water inside the waterfall is the motion of the projectile, so it has:

- a horizontal velocity which is constant: [tex]v_x = 2.90 m/s[/tex], since there are no forces acting along the horizontal direction

- a vertical motion which is an accelerated motion with constant acceleration, g=9.8 m/s^2, due to the effect of the force of gravity

The magnitude of the vertical velocity of the water when it hits the ground can be found by using

[tex]v_y^2 - u_y^2 = 2gh[/tex]

where

vy is the final velocity

uy=0 is the initial velocity

h = 206 m is the height of the waterfall

Solving for vy,

[tex]v_y = \sqrt{2gh}=\sqrt{2(9.8 m/s^2)(206 m)}=63.5 m/s[/tex]

so this is the vertical velocity of the  water as it hits the ground.

The magnitude of the overall velocity will be the resultant of the horizontal and the vertical components:

[tex]v=\sqrt{v_x^2+v_y^2}=\sqrt{(2.90 m/s)^2+(63.5 m/s)^2}=63.6 m/s[/tex]