Mr. Draper asks his class to design a system of gears, strings, and pulleys that will allow him to pull back the classroom's curtains simply by turning a crank at his desk. The system must be built within the following constraints:
It must be made only out of metal gears, metal pulleys, string, and one crank.
It must be strong enough to move the curtains.
It cannot be in the way of students or their desks.
It must take no more than one day to build.

The final design will use which type of energy to perform work on the curtains?
A.
kinetic energy
B.
elastic potential energy
C.
thermal energy
D.
gravitational potential energy

Explanation: When it cranks it is moving and the definition of kinetic energy is movement it can't be thermal because none of the resources or actions require heat. People could think it is elastic potential because it uses string and stuff but potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors. It can't be gravitational potential energy because one it says potential, potential has nothing to do with this. And it's not really gravitational because it is attached to something so it makes sense that it is kinetic energy.

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