Question

qr code #9
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check all that have a net force greater than zero.
a pumpkin sitting on a porch.
a bat landing in its cave.
a trick - or - treater running down the street with a constant speed of 5 m/s
halloween decorations hanging from a tree, blowing in the wind.
a spooky witch stirring a pot of her brew.

Explanation:

Step1: Recall net - force concept

Net force is zero when an object is in equilibrium (at rest or moving with constant velocity). Non - equilibrium implies non - zero net force.

Step2: Analyze pumpkin

A pumpkin sitting on a porch is at rest. Its net force is zero.

Step3: Analyze bat

A bat landing in its cave is changing its motion (decelerating), so it has a non - zero net force.

Step4: Analyze trick - or - treater

A trick - or - treater running with a constant speed of 5 m/s has zero acceleration and thus zero net force (assuming no non - balanced forces like wind resistance etc. affecting it in the horizontal direction).

Step5: Analyze decorations

Halloween decorations blowing in the wind are in non - uniform motion (changing direction and speed), so they have a non - zero net force.

Step6: Analyze witch

A witch stirring a pot is applying a non - balanced force on the brew, so there is a non - zero net force on the brew.

Answer:

A bat landing in its cave.
Halloween decorations hanging from a tree, blowing in the wind.
A spooky witch stirring a pot of her brew.