Jason is practicing his tennis stroke by hitting balls against a wall. The ball leaves his racquet at a height of 87.0 cm above the ground at an angle of 80.0 with respect to the vertical. If the speed of the ball as it leaves the racquet is 29.0 m/s, and if it must travel a distance of 21.0 m before it reaches the wall, what is the vertical component of velocity? Enter a positive value if the ball is upward and a negative value if the ball is downward. m/s