(A) We can find the time to reach the ground from the kinematic equation:
here, "y=55\\ m" is the vertical displacement of the ball (or the height of the building), "g=9.8\\ \\dfrac{m}{s^2}" is the acceleration due to gravity, "t" is the time to reach the ground.
Then, from this equation we can calculate "t":
(B) We can find initial horizontal velocity of the ball from the kinematic equation:
here, "x=35\\ m" is the horizontal displacement of the ball (or the horizontal range).
Than, we get:
(C) Let's firs find final vertical velocity from the kinematic equation:
The sign minus means that the final vertical velocity directed downward.
Finally, from the Pythagorean theorem we can find the velocity with which the ball will strike the ground:
Answer:
(A) "t=3.35\\ s."
(B) "v_{0x}=10.45\\ \\dfrac{m}{s}."
(C) "v=34.45\\ \\dfrac{m}{s}."
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