help with physics problem.

[Guest hello]

a projectile is fired from the top of a 40m tower at an angle of 60 degrees above horizontal hits the ground at the point 100 from the base of the tower.

 

 

find the speed at which the stone was thrown?

 

find the speed of the stone just before it hits the ground?

[Crash]

What level Physics are you in? find the horizontal component through trig, acceleration is 9.8 down, it will prob help to draw a picture

[mezarashi]

Given that you know the x-distance travelled and that velocity in x is constant due to the absence of any force field:

velocity initial X = (velocity initial) x (cos 60)

distance = velocity x time

100 meters = (velocity initial X) x time

 

In the y-component, similarly:

Velocity initial Y = Velocity initial x cos 60

distance = (velocity initial) x (time) + 1/2(acceleration x time^2) : your kinematics equation

 

40 meters = (velocity initial Y) x (time) + 1/2( g x time^2)

 

Two equations, two unknowns, solve simultaneously. The second problem can be solved using the component summation: velocity^2 = (velocity-X)^2 + (velocity-Y)^2