Answer:
A. 49 joules
Step By Step Solution:
Via kinematic equations we can must first determine the velocity of this object after 10 meters (since halfway of 20 meters is 10).
[tex]v_{final}^2=v_{initial}^2+2gd[/tex]
Where the initial velocity is zero since it's held at a height of 20 meters, hence it's not moving initially, g is the average gravity on Earth 9.8 m/s^2 and d is the distance this object will travel so 10 meters. By plugging these values in we obtain:
[tex]v_{final}^2=0+2(9.8)(10)\\\\v_{final}=\sqrt{2(9.8)(10)}=14m/s[/tex]
And the equation for kinetic energy is :
[tex]K.E.=\frac{1}{2}mv^2=\frac{1}{2}(0.5kg)(14m/s)^2=49J[/tex]
So the kinetic energy halfway after being released is 49 joules.
