What is the horizontal component of the boy's velocity?

Question

A boy jumps with a velocity of magnitude 20.0 m/s at an angle of 25.0° above the horizontal. What is the horizontal component of the boy's velocity?

Answer 1

We are given a vector of 20 m/s at an elevation of 25 degrees. Since we are looking for the horizontal, which is the adjacent, and because we are given the vector, which is our hypotenuse, we can use cosine to figure out our missing side.

 

cos25º=(adjacent/hypotenuse)

 

Which we substitute for

 

cos25º=(x/20m/s)

 

Which we can re-arrange as

 

x=20m/s * cos25º

 

Keeping your calculator in degrees, our answer is approximately

 

x=18.13