Question

carol and juan were playing with carols new train set. they pushed the trains around the track. they tried four different sections of track. what is the average speed of the train on track 4? a 40 cm/s b 240 cm/s c 6.66 cm/s d 10 cm/s track length (cm) travel time (s) 1 20 2 2 20 2 3 60 6 4 40 6

Explanation:

Step1: Recall speed formula

Speed $v=\frac{d}{t}$, where $d$ is distance and $t$ is time.

Step2: Calculate speed for Track 1

For Track 1, $d_1 = 20$ cm and $t_1=2$ s. So $v_1=\frac{d_1}{t_1}=\frac{20}{2}=10$ cm/s.

Step3: Calculate speed for Track 2

For Track 2, $d_2 = 20$ cm and $t_2 = 2$ s. So $v_2=\frac{d_2}{t_2}=\frac{20}{2}=10$ cm/s.

Step4: Calculate speed for Track 3

For Track 3, $d_3=60$ cm and $t_3 = 6$ s. So $v_3=\frac{d_3}{t_3}=\frac{60}{6}=10$ cm/s.

Step5: Calculate speed for Track 4

For Track 4, $d_4 = 40$ cm and $t_4=6$ s. So $v_4=\frac{d_4}{t_4}=\frac{40}{6}\approx6.66$ cm/s.

Step6: Calculate average speed

The average speed $v_{avg}=\frac{v_1 + v_2+v_3 + v_4}{4}=\frac{10 + 10+10 + 6.66}{4}=\frac{36.66}{4}=9.165\approx 10$ cm/s (rounded to the nearest whole - number).

Answer:

A. 10 cm/s