Answer:
Range formula: R = v^2 sin (2 theta) / g
If theta = 69 deg and v = 15.1
R = 15.1^2 sin 138 / 9,8 = 15.6 m
sin 138 = .669 = sin 42
So a snowball thrown at 21 deg will travel
R = 15.1 * .669^2 / 9.8 = 15.6 m
The second snowball can be thrown at 21 deg to travel the same distance
Vx = V cos theta = 15.1 * cos 69 = 5.41 first snowball
t1 = 15.6 / 5.41 = 2.88 sec
Vx = V cos theta = 15.1 cos 21 = 14.1 m/s
t2 = 15.6 / 14.1 = 1.11 sec
Difference = t1 - t2 = 1.77 sec time delay for second snowball
