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Answer:
mu = 0.56
Explanation:
The friction force is calculated by taking into account the deceleration of the car in 25m. This can be calculated by using the following formula:

v: final speed = 0m/s (the car stops)
v_o: initial speed in the interval of interest = 60km/h
= 60(1000m)/(3600s) = 16.66m/s
x: distance = 25m
BY doing a the subject of the formula and replace the values of v, v_o and x you obtain:

with this value of a you calculate the friction force that makes this deceleration over the car. By using the Newton second's Law you obtain:

Furthermore, you use the relation between the friction force and the friction coefficient:

hence, the friction coefficient is 0.56
The aluminum alloy(2024-T6; k=180 W/m<span>!K,) </span>absorber plate<span> is </span>6 mm thick<span> and </span>well insulated<span> on </span>its bottom<span>. The </span>top surface<span> of the </span>plate<span> is </span>separated<span> from a </span>transparent cover plate<span> by an </span>evacuated space<span>. The </span>tubes<span> are</span>spaced<span> a </span>distance<span> L of ...</span>
Answer:
The velocity is 
Explanation:
From the question we are told that
The speed of the roller coaster at ground level is 
Generally we can define the roller coaster speed at ground level using the an equation of motion as

u is zero given that the roller coaster started from rest
So

So

=> 
Now the displacement half way is mathematically represented as


So

Where
is the velocity at the half way point
=> 
=> 