When word is done on an object by an force, there will be a change in the total mechanical energy of the object. if forces do work total mechanical energy will be conserved.
a. internal, external
b. external, internal
c. internal, applied
d. none of the above

According to “Law of conservation of mechanical energy”, there would be change in total mechanical energy of the object, when INTERNAL forces is applied on object. If EXTERNAL forces are applied, when mechanical energy will be conserved.

Option A

Explanation:

When the object experiences an internal force, the mechanical energy of the closed system changes whereas when the object experiences an external force, the closed system do not have any change in the mechanical force, according to the law of conservation of mechanical energy.

answer and explanation;

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2