Haizal O.

asked • 08/06/14

Physics Work and Energy Question. Please check my answer.

A 5g apple is thrown straight upward with an initial velocity of 20 m/s @ a point of 1.5m height from ground. 
Ignoring air friction, find:
a. Total mechanical energy of the apple at initial position.
b. Total potential energy of the apple at maximum position. 
a) 5g = 0.005kg
    Kinetic Energy = (1/2)(m)(v)^2
                          = (1/2)(0.005)(20)^2
                          = 1J
b) Finding max position, 
    s = (u^2 - v^2)/(2a)
       = (20^2)/(2(9.81))
       = 20.39m
    Potential Energy = mgΔh
                            = (0.005)(9.81)(20.39-1.5)
                            = 0.9J
Is this correct? It feels wrong. Thank you in advance,

2 Answers By Expert Tutors


Bob A. answered • 08/06/14

4.9 (127)

20 Years Making Science and Maths Understandable and Interesting!

Haizal O.

Thank you Sir Stephen! Short and simple. Also thanks for the equation on my earlier question as well. (:


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