A ball is thrown straight upward and returns to the thrower’s hand after 2 s in the air. A second ball is thrown at an angle of 38 degrees with the horizontal. At what speed must the second ball be thrown so that it reaches the same height as the one thrown vertically? The acceleration of gravity is 9.8 m/s2.

Question

A ball is thrown straight upward and returns to the thrower’s hand after 2 s in the air. A second ball is thrown at an angle of 38 degrees with the horizontal. At what speed must the second ball be thrown so that it reaches the same height as the one thrown vertically? The acceleration of gravity is 9.8 m/s2.
Answer in units of m/s

bobpursley · Answer

It has to have the same vertical component of velocity original ball: Vf=Vi+gt -Vi-Vi=-9.8t Vi=4.9m/s second ball VsinTheta=4.9