Answer:
Step-by-step explanation:
We assume the graph is a plot of Sean's distance from home as he drives to work, works 8 hours, then drives home with a 2-hour stop along the way. It also appears that t is measured in hours after midnight.
The graph shows Sean's distance from home between 9 a.m. and 5 p.m. (t=17) is 20 km. Based on our assumptions, ...
Sean's workplace is located 20 km from his home.
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Speed is the change in distance divided by the change in time. Between 8 a.m. and 9 a.m. Sean's position changes by 20 km. His speed is then ...
(20 km)/(1 h) = 20 km/h
Sean's speed driving to work was 20 km/h.
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Between 5 p.m. (t=17) and 7 p.m. (t=19), Sean's position changes from 20 km to 10 km from home. That change took 2 hours, so his speed was ...
(10 km)/(2 h) = 5 km/h
Sean's speed between 5 p.m. and 7 p.m. was 5 km/h.
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<em>Additional comment</em>
The units of speed (kilometers per hour) tell you it is computed by dividing kilometers by hours. ("Per" in this context means "divided by".)
While the slope of the line on the graph between 5 p.m. and 7 p.m. is negative, the speed is positive. The negative sign means Sean's speed is not away from home, but is toward home. When the direction (toward, away) is included, the result is a vector called "velocity." Speed is just the magnitude of the velocity vector. It ignores direction.
