Question

(I just need to at least be shown...)
A soccer ball is kicked at an angle of 40 degrees from the ground at a speed of 30 m/s.

a) Describe which motion (horizontal of vertical) of the ball is constant and which is accelerated.
b) What are the vertical and horizontal components of the ball's initial velocity?
c) For what length of time is the ball in the air assuming the ground is flat and horizontal?
d) What is the range of the ball assuming the ground is flat and horizontal?

Answer 1

a) The motion that is constant is the horizontal when dealing with these types of parabolic trajectories...we know it cannot be the vertical because eventually it will change direction to fall back down

Answer 2

b) Well remember we basically just have a vector



And how do we break a vector into its components? Well, lets alter this a bit, what if we make it a right triangle?

Answer 3

How would we get the bottom side of that triangle? Notice it is just the 30 times the cosine of that angle right? Since cosine relates the adjacent (side we want) to the hypotenuse (side we have)

So if we just do 30cos(40) we will have the horizontal component of the trajectory

Similarly with the vertical part...we have the angle...and if we multiply that by the sine which relates opposite (again side we need) to the hypotenuse (again which we have) we get the vertical component

so 30sin(40) gives us that vertical component