F=ma
F= 4x1.2
F= 4.8 N
F= 4gsin30 - Friction
Friction= 19.6 - 4.8 N
Friction= 14.8 N
Friction= u x 4gcos30
14.8 / 4gcos30 = u
u= 0.43596...
u= 0.44
coefficient is 0.44
To solve this problem we will apply the concept related to the kinetic energy theorem. Said theorem states that the work done by the net force (sum of all forces) applied to a particle is equal to the change experienced by the kinetic energy of that particle. This is:


Here,
m = mass
v = Velocity
Our values are given as,


Replacing,


Therefore the mechanical energy lost due to friction acting on the runner is 907J
Here's a fun and useful factoid:
The ratio of the voltages on a transformer is the same
as the ratio of the number of turns in each winding.
So the ratio of (345 to the secondary turns) is (115V to 24V).
That's a proportion.
(115/24) = (345/x)
I'll bet you can take it and solve it from here.
Just cross-multiply in the proportion and etc. etc.
Red is the lowest because it has the shortest wavelengths
Acceleration = change in velocity/time
By F = ma,
6 = 33 x change in velocity / 9
change in velocity = +1.636 m/s