Answer:
10.6 meters.
Explanation:
We use the law of conservation of energy, which says that the total energy of the system must remain constant, namely:

In words this means that the initial kinetic energy of the roller coaster plus its gravitational potential energy minus the energy lost due to friction (1700j) must equal to the final kinetic energy at top of the second hill.
Now let us put in the numerical values in the above equation.




and solve for 

Notice that this height is greater than the initial height the roller coaster started with because the initial kinetic energy it had.
Answer:
B. W is positive and a is negative
Explanation:
As we know that the angular speed of the second clock is in positive direction so as it comes to halt from its initial direction of motion then we have
initial angular velocity is termed as positive angular velocity

now it comes to stop so angular acceleration is taken in opposite to the direction of angular speed
so we will have

so here correct answer is
B. W is positive and a is negative
D. Teach the public energy conservation
Well, <span>v = u + a×t is the equation.</span>
<span>
v: final velocity, which is 23 m/s in this equation.</span>
<span>u: initialo velocity = 13 m/s </span>
<span>a: acceleration = ? </span>
<span>t: time = 30s
</span>
Your equation would be...
<span>23 = 13 + a×30 </span>
<span>a = (23 - 13) / 30 </span>
<span>a = 1 / 3 </span>
<span>a = 0.333 m/s</span>