Question

A 0.100-kilogram apple hangs in a tree 1.50 meters above the ground. Ignoring frictional effects, the total mechanical energy of the apple is _____.

A)0.00 J
B)less than 1.47 J but more than 0.00 J
C)exactly 1.47 J
D)more than 1.47 J
correct answer :c

Answer 1

C)exactly 1.47 J

Step-by-step explanation:

The mechanical energy of a body or a system is the sum of its potential energy and kinetic energy

`E_m=E_p+E_k`

Data

`m= 0.1Kg\\h=1.50m\\g(gravity)=9.8m/s^2`

To find the mechanical energy we must first find out what is its potential energy and its kinetic energy

`E_p= m.g.h\\E_p=0.1Kg. 9.8m/s^2.1.50m\\E_p= 1.47J`

`E_k= (1)/(2)m.V^2`

As we observe in the formula the kinetic energy depends on the speed of the body, but in this case the body is not moving, it is only found hanging at rest, therefore its speed is zero

`E_k= (1)/(2)0.1Kg.0\\ E_k= 0`

as the body has no speed the kinetic energy is zero

Now we calculate the mechanical energy

`E_m=E_p+E_k\\E_m=1.47J+0\\E_m=1.47J`

The mechanical energy is 1.47J. The correct option is C