18) Question 18 is asking us to identify the graph that best suits the situation given in the problem. A block is slid up and down a rough incline. To solve this problem, we should look at the velocity and the forces acting on the block at each section of the motion.
We can start with the section when the block is sliding up the incline.
Since the acceleration is in the opposite direction of the velocity, we know that the object will eventually come to rest. After that, the block will slide down the incline.
On the way down, the net force is going in the same direction as the velocity so the speed is increasing.
When we look at the sum of the forces, when sliding up the incline, the friction and gravity both point down the incline, making the magnitude of the net force greater than when the mass slides down the incline. And since the force is greater, the net acceleration of the block while sliding up the incline will be greater than when sliding down the incline.
This matters because it tells us that the magnitude of the slope should be greater when the object slides down the incline than when the object slides up the incline. Thus, the answer must be B.
Answer: B
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