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I got these three wrong on an exam, I cannot for the life of me figure out what

ID: 1621382 • Letter: I

Question

I got these three wrong on an exam, I cannot for the life of me figure out what the correct answers are. My answers are circled so they must not be the correct answers.

Problems 9-11: An object is moving along a straight line in the positivex direction. The graph be below shows its position from the starting point as a function of time. x (m) of- t (s) 12 16 20 12 9/ What is the velocity of the object at t 14 s? A) +1.0 m/s B) 1.0 m/s C) 0.2 m/s D) zero m/s E) None of the above 10 During which interval(s) did the object move in the negative x direction? A) only from 8 s to 14 s B) only from 4 s to 8 s C) only from 0 s to 2 s t D) only from 8 s to 20 s E) The object never moved in the negative x direction.

Explanation / Answer

9) let the final speed of the object is v

from the graph

as speed = slope of the x-t curve

speed = (-6 - (6))/(20 - 8)

speed = -1 m/s

the velocity of the object is -1 m/s

10)

object move in negative direction when the slope of graph is negative

the time interval is from t= 8 s to t = 20 s