Question

diego is trying to lift a piano to the second floor of his house. diego uses a pulley system and gives a big lift to the piano. the piano moves upward, then stops, and then it starts to fall to the ground. (the direction of the force of gravity is negative.) which list best describes the forces on the piano in the proper order? positive force → balanced force → negative force negative force → balanced force → positive force positive force → unbalanced force → negative force negative force → unbalanced force → positive force

Explanation:

Step1: Analyze upward - moving phase

When Diego gives a big lift to the piano and it moves upward, the force he applies (using the pulley system) is greater than the force of gravity. Since the direction of the force of gravity is negative, the force applied by Diego is a positive force.

Step2: Analyze when the piano stops

When the piano stops moving upward, the force applied by Diego and the force of gravity are equal in magnitude. At this point, the forces are balanced.

Step3: Analyze when the piano falls

When the piano starts to fall to the ground, the force of gravity (negative - direction) is greater than any upward - acting force. So, it is under the influence of a negative force.

Answer:

positive force → balanced force → negative force