Answer:
We obtain the average velocity instead of the instantaneus velocity.
Explanation:
The problem with calculating speed in this way is that an average speed is being calculated and not an instantaneous speed at a given point.

To calculate the instantaneous speed, a very small space interval must be measured at a given time.
The amount of friction depends on the force pushing the surfaces together. If this force increases, the hills and valleys of the surfaces can come into closer contact. The close contact increases the friction between the surfaces.
Answer:

Explanation:
The final angle speed of the merry-go-round is determined with the help of the Principle of Angular Momentum Conservation:
![(270\,kg\cdot m^{2})\cdot \left(8\,rpm\right) = [270\,kg\cdot m^{2}+(27\,kg)\cdot (1.80\,m)^{2}]\cdot \dot n](https://tex.z-dn.net/?f=%28270%5C%2Ckg%5Ccdot%20m%5E%7B2%7D%29%5Ccdot%20%5Cleft%288%5C%2Crpm%5Cright%29%20%3D%20%5B270%5C%2Ckg%5Ccdot%20m%5E%7B2%7D%2B%2827%5C%2Ckg%29%5Ccdot%20%281.80%5C%2Cm%29%5E%7B2%7D%5D%5Ccdot%20%5Cdot%20n)

I hope the wire is not wound too tightly around the bar magnet.
The device will generate electrical energy when the bar magnet
is moving in or out of the coil of wire.
<h2>
Entire trip takes 1.22 seconds.</h2>
Explanation:
We have equation of motion s = ut + 0.5 at²
Initial velocity, u = 0 m/s
Acceleration, a = 9.81 m/s²
Time, t = 0.866 s
Substituting
s = ut + 0.5 at²
s = 0 x 0.866 + 0.5 x 9.81 x 0.866²
s = 3.68 m
Halfway is 3.68 m
Total height = 2 x 3.68 = 7.36 m
We have equation of motion s = ut + 0.5 at²
Initial velocity, u = 0 m/s
Acceleration, a = 9.81 m/s²
Time, t = ?
Displacement, s = 7.36 m
Substituting
s = ut + 0.5 at²
7.36 = 0 x t + 0.5 x 9.81 x t²
t = 1.22 s
Entire trip takes 1.22 seconds.