Answer:
The coefficient of kinetic is

Explanation:
The forces in the axis 'x' and 'y' using law of Newton to find coefficient of kinetic friction
ΣF=m*a
ΣFy=W-N=0
ΣFy=Fn-Fu=m*a


Now to find the coefficient can find the acceleration using equation of uniform motion accelerated

So replacing the acceleration can fin the coefficient:

Answer:
40 s
Explanation:
After 10 seconds, the first skater would have a 8m/s * 10s = 80 m head start
Let t be the number of seconds after the second skater starts will the second skater overtake the first skater
The distance traveled by the first skater after t seconds is

Similarly the distance traveled by the 2nd skater after t seconds is

Since the 2nd skater catches up to the 1st one after 80 m behind, the distance traveled by the 2nd one must be 80m greater than the distance of the 1st skater

We can substitute 



Answer:
This is due to impulse
Explanation:
Impulse equal to mΔv and FΔt
You can set these equal as mΔv = FΔt
When a boxer punches a tissue, it is like punching a cushion or a pillow. The time that the hit takes is much grater than if they were to hit something solid. In addition, the change in velocity of the boxer's arm would be much greater when they hit a punching bag. In this equation, the greater the time, the less force that is needed.
Answer:
A I think
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Answer:
h = 9.57 seconds
Explanation:
It is given that,
Initial speed of Kalea, u = 13.7 m/s
At maximum height, v = 0
Let t is the time taken by the ball to reach its maximum point. It cane be calculated as :




t = 1.39 s
Let h is the height reached by the ball above its release point. It can be calculated using second equation of motion as :

Here, a = -g


h = 9.57 meters
So, the height attained by the ball above its release point is 9.57 meters. Hence, this is the required solution.