Tennis ball velocity

Question

A tennis ball hit down at an angel of 30° below the horizontal from the height of 2m. It is initially traveling at 5.0m s^-1. what is the velocity of the ball when it hits the ground of we can neglect air resistance?

Answer 1

Let v_0y= 5sin30° =2.5 m/s and v_0x = 5cos30° = 4.33m/s 2m= v_0yt + at²/2 = 2.5t + 4.9t² and equation becomes 4.9t² +2.5t -2 =0 use the quadratic formula to solve for t to get t=.433s which gives v_y = 2.5 + 9.8•.433 = 2.5 + 4.24 = 6.742 m/s and the velocity at impact is v= √(6.742² + 4.33²) = 7.89 m/s.