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Question 46521:
Good evening, i have this problem about physic. i can not work out .Please would u work for me ?
Potential gravitational enery( defined as 'mass' mulitiplied by 'gravitational acceleration' by "height" - or mgh ) is one form of energy, and and kinetic energy ( defined as half the product of 'mass' mulitiply by 'velocity squared' - or mv2/2 ) is another. Assuming the conservation of energy ( and that there are no resisting forces ), from what height would a car have to fall to gain the kinetic energy it it would have when going at 60 kilometers per hour?
Please solve this problem for me.
Yours faithful student Emma Mode
Answer by Earlsdon(6294)   (Show Source):
You can put this solution on YOUR website! Start by letting P = Potential gravitational energy = mgh.
Let K = kinetic energy = 
To answer the question, you should set the potential gravitational energy, P equal to the kinetic energy, K
 Simplify this by dividing both sides by m.
 Solve for h, the height.
v is the velocity of the car (60 kmph) and you will need to convert this to metres per second.
60 km = 60,000 metres
1 hour = 3,600 secs
So, 60 kmph = 60,000m per 3,600 secs. Simplifying this we get:
v = 16.67 m/sec. Square this for 
 m^2/sec^2
g (the gravitational constant of acceleration) is 0.98 m/sec^2
Now you can find the height, h.
 metres
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