Question

multiple choice 0.5 points
what is the average velocity from b (10 s, 52 m) to c (20 s, 38 m)?
table 2.1 position of
the car at various times
position \t t (s) \t x (m)
a \t 0 \t 30
b \t 10 \t 52
c \t 20 \t 38
d \t 30 \t 0
e \t 40 \t -37
f \t 50 \t -53
+1.4 m/s
-1.4 m/s
-0.7 m/s
+0.7 m/s

Explanation:

Step1: Recall average velocity formula

Average velocity is $\bar{v} = \frac{\Delta x}{\Delta t} = \frac{x_2 - x_1}{t_2 - t_1}$

Step2: Identify given values

For position B: $t_1=10\ \text{s}$, $x_1=52\ \text{m}$; For position C: $t_2=20\ \text{s}$, $x_2=38\ \text{m}$

Step3: Calculate displacement $\Delta x$

$\Delta x = x_2 - x_1 = 38 - 52 = -14\ \text{m}$

Step4: Calculate time interval $\Delta t$

$\Delta t = t_2 - t_1 = 20 - 10 = 10\ \text{s}$

Step5: Compute average velocity

$\bar{v} = \frac{-14}{10} = -1.4\ \text{m/s}$

Answer:

-1.4 m/s