Projectile motion

1. The problem statement, all variables and given/known data

This is a review question from the test I did few months back, and I need to review it for my finals.

A ball is thrown from the top of a building 35m high with an initial speed of Vi at an angle 30° above the horizontal. The ball strikes the ground at a point 80m from the base of the building. Find

a) the time of the ball is in the flight
b) the horizontal and vertical component of the initial velocity
c) its initial velocity and
d) the velocity of the ball just before it strikes the ground

2. Relevant equations

Sy= Viy t + 1/2Ayt^2

3. The attempt at a solution

My attempt was resolving into x and y direction, so,

Ax= 0 Ay=-9.8m/s
Sx= 80m Sy=-35, Viy= 0

Therefore: Sy= Viy+1/2Ayt^2
-35= 0 + 1/2(-9.8)t^2
Finally: My t = 2.67s

Apparently, I was marked wrong, so my time I found is wrong and therefore I couldn’t proceed with b,c and d with the wrong time.

Help would be really appreciated! Thanks.

http://ift.tt/1nruDeV

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