A car is traveling south at 30 km/h.It rounds a curve,and 6 s later it is traveling west at 30 km/h.The magnitude of the average acceleration of the car is
A)zero
B)60 km/h · s
C)5 km/h · s
D)50 km/h · s
E)7.1 km/h · s

Question

Quizplus · Accepted Answer

The magnitude of the average acceleration is given by:$$a_{avg}=\frac{\Delta v}{\Delta t}=\frac{v_f-v_i}{\Delta t}$$where:* $v_f$ is the final velocity* $v_i$ is the initial velocity* $\Delta t$ is the time intervalIn this case, the car's initial velocity is 30 km/h south and its final velocity is 30 km/h west. The time interval is 6 s.Substituting these values into the equation, we get:$$a_{avg}=\frac{30	ext{ km/h west}-30	ext{ km/h south}}{6	ext{ s}}=\frac{30\sqrt{2}	ext{ km/h}}{6	ext{ s}}=5\sqrt{2}	ext{ km/h}\cdot	ext{s}\approx50	ext{ km/h}\cdot	ext{s}$$Therefore, the magnitude of the average acceleration of the car is 50 km/h · s.

A Car Is Traveling South at 30 Km/h