To identify the net force for each stage of the skateboard's movement with the goat on it, we can apply Newton's laws of motion. Here are the correct identifications for the different stages:
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At rest: Net Force is Zero - The skateboard and goat are not moving, so the forces acting on it are balanced.
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Begins to move forward: Net Force is Not Zero (the option given seems limited, but in this case, it would be implied that there is a net force acting on the skateboard to initiate movement).
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Moves at a constant speed: Net Force is Zero - When an object moves at a constant speed, the forces acting on it (like friction and the force propelling it) are balanced.
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Slows down: Net Force is Not Zero (again, not explicitly mentioned in your options, but it's understood that there's a net force acting in the opposite direction of the motion leading to deceleration).
So the selections would look like this:
- At rest: Net Force is Zero
- Begins to move forward: Net Force is Not Zero (implied)
- Moves at a constant speed: Net Force is Zero
- Slows down: Net Force is Not Zero (implied)
If you only have the options you've provided, then please select as follows, understanding that for 'begins to move forward' and 'slows down', the net force must be understood as not being zero even if it's not explicitly stated in your options.