Question

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1. describing motion what are three ways an object can accelerate?
2. position - time and velocity - time graphs two joggers run at a constant velocity of 7.5 m/s east. figure 10 shows the positions of both joggers at time t = 0.

a. what would be the difference(s) in the position - time graphs of their motion?
b. what would be the difference(s) in their velocity - time graphs?

Explanation:

1. Acceleration is a change in velocity. Velocity is a vector with magnitude (speed) and direction. So an object can accelerate by changing its speed (speeding up or slowing down), changing its direction of motion, or changing both speed and direction simultaneously.

12.a. Since they have the same velocity but different initial positions (one is 15 m west and the other is 15 m east of the origin at t = 0), the position - time graphs will be parallel straight - lines (because of constant velocity), but with different y - intercepts. The jogger starting 15 m west will have a negative y - intercept and the jogger starting 15 m east will have a positive y - intercept.
12.b. Since they both have a constant velocity of 7.5 m/s east, their velocity - time graphs will be identical horizontal lines at v = 7.5 m/s. There will be no difference.

Answer:

1. Speeding up, slowing down, changing direction.

12.a. Different y - intercepts, parallel lines.
12.b. No difference.