Identify the forces acting on the object of interest. from the list below, select the forces that act on the piano.

1. acceleration of the piano
2. gravitational force acting on the piano (piano's weight)
3. speed of the piano
4. gravitational force acting on chadwick (chadwick's weight)
5. force of the floor on the piano (normal force)
6. force of the piano on the floor
7. force of chadwick on the piano
8. force of the piano pushing on chadwick

The correct answer is the following.

The forces that act on the piano are: 2) gravitational force acting on the piano (piano's weight). 5) force of the floor on the piano (normal force). 7) force of Chadwick on the piano.

As we see in the picture that I have attached is Chadwick pushing the piano in a horizontal plane. So Chadwick is applying a force that produces an acceleration. It is his force on the piano plus the acceleration of the weight of the piano, it's a gravitational force. This is pure physics applied to an object.

we need to know the time interval during which the force acts. impulse of force = momentum change

365.25 earth days are in the year of a light year