A jumper in the long-jump goes into the jump with a speed of 12 m/s at an angle of 20° above the horizontal. How long is the jumper in the air before returning to the Earth?
A) 0.21 s
B) 0.42 s
C) 0.84 s
D) 1.3 s
E) 1.6 s

Question

Quizplus · Accepted Answer

First, we need to find the initial vertical and horizontal components of the velocity.

Vertical: 
v_y = v*sin(20°) = 12*sin(20°) = 4.09 m/s

Horizontal: 
v_x = v*cos(20°) = 12*cos(20°) = 11.01 m/s

Next, we can use the vertical component to find the time of flight:

v_y = gt/2 
4.09 = 9.81*t/2 
t = (2*4.09)/9.81 = 0.84 s

Therefore, the jumper is in the air for 0.84 seconds before returning to the Earth.

A Jumper in the Long-Jump Goes into the Jump with a Speed