# Projectile motion of shotputter

steve snash

## Homework Statement

A shotputter throws a shot with an initial speed of 15.5m/s at a 34.0 degree angle to the horizontal. Calculate the horizontal distance given that the shot leaves the athletes hand 2.2m above the ground???

## Homework Equations

Distance=((initial velocity)^2 x sin (2xdegrees))/gravity(9.8)

Although this is the level range formula used when height final = height of initial. How do you change this formula to accommodate the fact that the shot lands 2.2m lower than it started????????

## The Attempt at a Solution

d=15.5^2 x sin 68/ 9.8 =29.09m, I know this must be wrong but i have read through the text book and it does not help me at all in finding how to work this out. I shows what to do if the degrees is not given but with the degrees what equation can i use??????????????

WiFO215
There isn't any point by-hearting formulae such as the one above. Use the equations of motion for constant acceleration,
v = u + at
s = ut + at2/2
v2 = u2 + 2as

where u and v denote initial and final velocities, a denotes acceleration, and s denotes displacement.

steve snash
Yeah but none of them incorporate the angle of release given???? Im guessing thats an important variable, so shouldnt it be used

Homework Helper
Initial height yo of the shot put is given.At the end it reaches the ground. So the final height y = 0
So
y = yo + Vo*sinθ*t - 1/2*g*t^2.
Solve for t. Then horizontal distance
x = Vo*cosθ*t.
Now solve the problem.

Last edited:
steve snash
0=2.2+15.5*sin 34*t-1/2*9.8*t^2
t=-0.225
x=15.5*cos 34*-0.225
x=-2.8912
this answer does not make sense

Homework Helper
Negative time is not possible. While solving the quadratic equation, you will get two values of t. You have to select the positive value of t.

Last edited:
steve snash
alright, cheers