A baseball is thrown at an angle of 40.0° above

the horizontal. The horizontal component of the

baseball's initial velocity is 12.0 meters per

second. What is the magnitude of the ball's initial

velocity?

(1) 7.71 m/s (3) 15.7 m/s

(2) 9.20 m/s (4) 18.7 m/s

Imagine you have a triangle at angle 40.

initial velocity = m/sec

12 is the horizontal component, so it is the cosine side, so you must find cosine (40) for the angle.

then you have to divide 12/cos (40) to get 15.7 m/s as your initial velocity

Vector trigonometry can be used for this problem. Since the horizontal component is 12 meters per second, this is technically the hypotenuse (actual initial velocity) multiplied to cosine of 40 degrees. Therefore, to find the hypotenuse, we must divide 12 by cosine 40degrees. cos (40) = 0.766, and 12/0.766 = approximately 15.664, therefore our answer is (3) 15.7 m/s