A 5.0 kg block of wood sits on a concrete floor. The largest horizontal force that can be applied to the block before it will start moving is 22.7 N. Once the block starts moving, it only takes 16.8 N to keep
moving at a constant velocity.
a) Calculate the coefficient of static friction for the block and the floor.
(2A)
b) Determine the force of friction acting on the block if a horizontal force of 12.8 N (E) acts on
the block.
(1A)
c) Determine the coefficient of Kinetic friction.
[2A]
please help and don't send answer in link​

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.