Concept explainers
A teacher stands in the middle of a parking lot and watches a small child peddle a tricycle around the lot. At time t = 0, the child is due north of the teacher, traveling west. Thirty seconds later, the child is due west of the teacher, traveling south. What are the directions of the child’s (a) displacement, (b) average velocity, and (c) average acceleration? Express your answers in terms of these general directions: N of W, S of W, N of E, and S of E.
(a)
The direction of child’s displacement.
Answer to Problem 1CQ
The direction of child’s displacement is
Explanation of Solution
The free body diagram is given below.
Displacement is the shortest distance between the initial and final positions. It is equal to the line joining the two points corresponding to child’s motion is the displacement. Therefore, the displacement is directed along south of west.
(b)
The direction of child’s average velocity.
Answer to Problem 1CQ
The direction of child’s average velocity is
Explanation of Solution
The free body diagram is given below.
Average velocity is defined as the rate of change of displacement. It’s direction is same as that of displacement. Therefore, the average velocity is directed along south of west.
(c)
The direction of child’s average acceleration.
Answer to Problem 1CQ
The direction of child’s average acceleration is
Explanation of Solution
The free body diagram is given below.
Average acceleration is defined as the rate of change of velocity. It’s direction is perpendicular to the line of displacement. Therefore, the average acceleration is directed along south of east.
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