Section 1 review
Acceleration is the rate at which velocity changes. Its SI unit is meter per second squared, or m/s2. Acceleration is a vector. In one-dimensional motion, acceleration can be positive or negative (as well as zero). The slope of the velocity–time (v vs. t) graph is the acceleration. The area under a velocity–time graph equals an accelerating object’s displacement. Read the text aloud
acceleration, quadratic

a= Δv Δt
v= v 0 +at
x= x 0 + v 0 t+ 1 2 a t 2
x= x 0 + 1 2 ( v 0 +v )t
v 2 = v 0 2 +2a( x x 0 )

Review problems and questions

  1. Two friends each drive a car down Highway 101. During the same 10 s interval, Jodi’s car moves at a constant 60 mph and Julie’s car transitions from a speed of 20 mph to a speed of 30 mph.
    1. Whose car has the greater acceleration?
    2. Do you have to convert the given quantities into SI units in order to figure out which car has the greater acceleration? Read the text aloud Show
Position-time graphs for three sprinters
  1. The position–time graphs of three sprinters are shown here. Which sprinter best matches each of the following statements?
    1. “I underwent positive acceleration during the three-second interval shown.”
    2. “I underwent negative acceleration during the three-second interval shown.”
    3. “I underwent zero acceleration during the three-second interval shown.” Read the text aloud Show
Nikita and Rachel are driving on the highway
  1. Nikita and Rachel are driving their new cars westward on the highway. At the very same instant, they cross the Weston town line (call it t = 0). Nikita’s velocity is 20 m/s westward at that moment, while Rachel is going faster at 30 m/s (in the same direction). Each driver is accelerating westward: Nikita at 3 m/s2, and Rachel at 1 m/s2. They maintain these accelerations for 10 s (until t = 10 s).
    1. At what time t are Nikita and Rachel equally fast?
    2. At that time (when they are equally fast), who has gone farther from the town line?
    3. After 10 s has passed (that is, at t = 10 s ), who is farther from the town line? Read the text aloud Show

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