A giant rolls a bowling ball with a uniform speed of 30 m/s (about 70 mph) across the top of his la
问题描述：
A giant rolls a bowling ball with a uniform speed of 30 m/s (about 70 mph) across the top of his la
A giant rolls a bowling ball with a uniform speed of 30 m/s (about 70 mph) across the top of his large desk.The ball rolls off the edge of the desk and lands on the floor 120 m from the edge of the desk.How high is the desk?
how do I do
答
120 (m) / 30 (m/s) = 4 secs,which means the ball stayed in the air for 4 secs,that gives the height of the desk,which is1/2 gt^2 = 0.5 x 9.8 x (4) ^ 2 = about 80 m