Asked by Malcolm

The car shown in the figure has a mass of 395 kg when it passes through point A with a speed of 17.7 m/s, being the height of A 7.2 m above the ground (y = 0). In the instant that passes through C its speed is diminished to 7.6 m/s. Assuming that the path has no friction

(a) What is the height of point C?

(b) What is the mechanical energy at point B relative to the ground?

I already solved a part which gave me 20.24m

I need help with part b, thanks in advance!
Answered by Damon
at start
E = (1/2) m v^2 + m g h
E = (1/2)(395)(17.7)^2 + 395*9.81*7.2
= 61875 + 27900 = 89775 Joules

at C
89775 = (1/2)395(7.6)^2+395*9.81*h

h = [ 89775 - 11408] / (3875)
h = 20.22
so agree but part b is trivial:
89775 is the total mechanical energy forever and ever by the way if there is not friction
Answered by Malcolm
Yes, I forgot about the concept of conservation. Thank you!
Answered by Damon
But, but, conservation is in your title !!!!
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