Answer:
C. 98 J
Explanation:
Mechanical energy is defined as the sum of kinetic energy (K) and potential energy (U):
E = K + U
where
\(K=\frac{1}{2}mv^2\) is the kinetic energy, where m is the mass of the object and v its speed
\(U=mgh\) is the potential energy, where g is the gravitational acceleration and h the height of the object relative to a reference point
For the object in this problem, the kinetic energy is zero, because it is not moving, so v = 0 and K=0. So the mechanical energy is just given by the potential energy, which is given by:
\(E=U=mgh=(1 kg)(9.8 m/s^2)(10 m)=98 J\)
