Question

which statement best describes a machine?
a machine makes work easier by changing the strength or direction of a force.
a machine decreases the amount work by increasing the strength of a force.
a machine makes work easier by increasing the strength of a force.
a machine makes work easier by decreasing the strength of a force.

Explanation:

A machine's function is to simplify work. It does this by altering either the strength (e.g., using a lever to lift a heavy object with less force) or the direction (e.g., using a pulley to lift an object upward by pulling downward) of an applied force. Work \(W = F\times d\) (force times distance) remains the same in an ideal machine (neglecting friction). So a machine doesn't decrease the amount of work. Options that only mention increasing or decreasing force strength (without considering direction) are too narrow.

Answer:

A. A machine makes work easier by changing the strength or direction of a force.