posted by Kate .
A discus is thrown from a height of 3 feet with an initial velocity of 55 ft/s at an angle of 44° with the horizontal. How long will it take for the discus to reach the ground?
I started off with 55cos(44)=40
then I made an equation
I feel like I did this wrong because I didn't add 3 feet anywhere
or do I add 3 in to 55cos(44) giving me an answer of 2.6
Yes, the 3 feet are important.
You can consider the datum (y=0) at 3' from the ground, and the ground is therefore at -3 feet.
The vertical initial velocity, vy, is u*sin(θ), so it gives
The (vertical) distance travelled is given by:
Solve for t.
I get -0.08 and 2.45 s.