Projectile Motion: Time, Distance, and Velocity in 2D

[blue__boy]

A cannon ball is fired horizontally at a speed of 1000.0m/s from a height of 200.0m

a.) How long does it take for the ball to land?
6.39s
b.) Where does it land?
6390m
c.) What is its velocity when it lands?



I get the a and b part...but i just don't understand what am i supposed to do with c.)

Thx for helping =]

 

[Rake-MC]

You can use constatnt acceleration formulae to calculate the y velocity and the x velocity as it lands seperately.
Because the y and x axes are perpendicular to each other, you are able to use pythagoras' theorem to calculate the total velocity (the hypotenuse in this case).

 

[blue__boy]

oh...i am having trouble finding the vertical velocity too...

 

[Rake-MC]

initial vertical velocity = 0ms^-1, because it is only fired horizontally (no vertical components).
height = 200m
acceleration = -9.81ms^-2

we can use the constant acceleration formulae: v_f^2 = v_i^2 + 2as --> Where s is displacement.