Hello!! 
Here we have a simple matter of conservation of energy. ME=PE+KE. 
At point A we have PE=mgh and KE=1/2mv^2. At point A all we have is PE since the coaster isn’t rolling yet. But by conservation of energy, we know that it will have enough energy to roll down and get to and equal height on another hill. Providing we are neglecting friction and drag and resistance forces which we are in this case. So we can conclude that the KE will be greater at Point B since ME=PE+KE and for ME to remain the same and we know the PE is less on lower hill, so we can conclude that KE on lower hill is greater to keep ME the same and have conservation of energy. 
Hope this helps you understand the concept!! Any questions please just ask!! Thank you so much!!
        
             
        
        
        
Answer:
the relative speed should be 40mph
Explanation:
 
        
             
        
        
        
<u>Answer</u>
5.the stage before a star becomes a main sequence star
<u>Explanation</u>
A protostar is a small star that is still gathering its masses. When it forms enough masses it make a parent molecular cloud.
This been the case, from the choices given, the correct statement about a protostar is;
5.the stage before a star becomes a main sequence star
 
        
                    
             
        
        
        
Incomplete question as the mass of baseball is missing.I have assume 0.2kg mass of baseball.So complete question is:
A baseball has mass 0.2 kg.If the velocity of a pitched ball has a magnitude of 44.5 m/sm/s and the batted ball's velocity is 55.5 m/sm/s in the opposite direction, find the magnitude of the change in momentum of the ball and of the impulse applied to it by the bat.
Answer:
ΔP=20 kg.m/s
Explanation:
Given data
Mass m=0.2 kg
Initial speed Vi=-44.5m/s
Final speed Vf=55.5 m/s
Required
Change in momentum ΔP
Solution
First we take the batted balls velocity as the final velocity and its direction is the positive direction and we take the pitched balls velocity as the initial velocity and so its direction will be negative direction.So we have:

Now we need to find the initial momentum
So

Substitute the given values 

Now for final momentum

So the change in momentum is given as:
ΔP=P₂-P₁
![=[(11.1kg.m/s)-(-8.9kg.m/s)]\\=20kg.m/s](https://tex.z-dn.net/?f=%3D%5B%2811.1kg.m%2Fs%29-%28-8.9kg.m%2Fs%29%5D%5C%5C%3D20kg.m%2Fs)
ΔP=20 kg.m/s