Force and Motion Retest
4 of 204 of 20 Items
Question
Megan left her wagon outside while it was raining and it filled with water. When Megan tried to move the wagon that afternoon, she failed to budge the wagon. Why did Megan's wagon become hard to move?
Responses
The rainwater decreased the force of gravity pushing on the wagon, increasing the force needed to move it.
The rainwater decreased the force of gravity pushing on the wagon, increasing the force needed to move it.
The rainwater decreased the force of friction pulling on the wagon, decreasing the force needed to move it.
The rainwater decreased the force of friction pulling on the wagon, decreasing the force needed to move it.
The rainwater increased the mass of the wagon, decreasing the amount of force needed to move it.
The rainwater increased the mass of the wagon, decreasing the amount of force needed to move it.
The rainwater increased the mass of the wagon, increasing the amount of force needed to move it.
The correct response is:
The rainwater increased the mass of the wagon, increasing the amount of force needed to move it.
The additional mass from the rainwater means that Megan would need to apply more force to overcome the wagon's inertia and set it in motion. The increased mass does not affect the force of gravity in a significant way on such a small scale (gravity acts on all masses uniformly); it's the added weight—which is essentially the force due to gravity acting on the added mass of the water—that makes the wagon harder to move. The amount of force needed to move an object is directly related to its mass; the greater the mass, the more force is required.