Total energy of an object.

  • Thread starter Sixty3
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  • #1
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Homework Statement


If a question asks to calculate total energy of an object that does have a horizontal velocity (constant, air resistance ignored), and it is at it's highest point so it's vertical velocity is zero.

I need to know how you'd calculate the total energy of this object.

Let's take mass as 5kg. And a highest point of 3m. Horizontal velocity of 2m/s. (I just made them up).


Homework Equations


Potential energy = mgΔh
Kinetic energy = 0.5mv^2


The Attempt at a Solution


Pe= 5*9.81*3 = 147.15J
Ke= 5*2^2= 20/2 = 10J

10+147.15= 157.15J

I was just wondering if I am not leaving anything out, or if I'm even doing it correct! Thanks
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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Hi Sixty3 :smile:

(try using the X2 tag just above the Reply box :wink:)
Let's take mass as 5kg. And a highest point of 3m. Horizontal velocity of 2m/s. (I just made them up).

Pe= 5*9.81*3 = 147.15J
Ke= 5*2^2= 20/2 = 10J

10+147.15= 157.15J

I was just wondering if I am not leaving anything out, or if I'm even doing it correct! Thanks

Yes, that's fine …

at launch, and when on return to the ground, its KE is 157.15J.

(btw, we normally put a capital 'E' in KE and PE :wink:)
 

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