Question

D
An athlete jumps with a speed of 4 m/s at a angle of 23 degrees. How long does the athlete stay in the air?

Answer 1

it would be 4sin(23) right?

Answer 2

that's the right start but there's a little more work to be done

the initial y velocity is 4sin(23)

so using our kinematics equation

vf = vi + at

plug in vf = 0 (since we want the time it takes to reach the top of the parabola where velocity final = 0)

vi is the initial velocity 4sin(23)

a is the acceleration due to gravity

and solve for t

Answer 3

0 = 4sin(23) + (9.8)t

Answer 4

like this right?

Answer 5

almost, g needs to be negative, so -9.8 (downward acceleration)

Answer 6

okay i got 0.16

Answer 7

good, now that's only half way on the parabola, so just double that to get the entire journey, which is 0.32s ==> answer C