my guess would be the sphere. i'm not very good at physics but i think it would be the sphere because it can roll, while the cube can't. the cube may be able to slide, but may eventually stop. it may be easier to push a sphere up a ramp better.
the law of reflection states that the angle of reflection is equal to the angle of inkidence .
i believe that it is b
consider the upward direction of motion as positive and downward direction of motion as negative.
a = acceleration due to gravity in downward direction = - 9.8
v₀ = initial velocity of rock in upward direction = ?
v = final velocity of rock at the highest point = 0
t = time to reach the maximum height = 4.2 sec
using the kinematics equation
v = v₀ + a t
inserting the values
0 = v₀ + (- 9.8) (4.2)
v₀ = 41.2