Question

warm - up exercises
exercise 1: in a boat race, lina took a big lead and went the 100 - meter course from start to finish in 40 seconds. what was linas average speed during the race?
exercise 2: it takes tanya 0.25 hours to drive to school. her route is 16 km long. what is tanyas average speed on her drive to school?
exercise 3: in a competition, an athlete threw a flying disc 138 meters through the air. while in flight, the disc traveled at an average speed of 13.0 m/s. how long did the disc remain in flight?
exercise 4: if you shout into grand canyon, your voice travels at the speed of sound (340 m/s) to the bottom of the canyon and back, and you hear an echo. how deep is the grand canyon in a spot where you can hear your echo 5.2 seconds after you shout?
exercise 5: sound travels much faster in water than air. it takes 4.2 seconds for the sound of an explosion to travel underwater to a diver 6,006 m away. what is the speed of sound in water?

Explanation:

Step1: Recall average speed formula

Average speed: $v = \frac{d}{t}$, where $d$ = distance, $t$ = time
---

Exercise 2

Step2: Identify given values

$d = 16\ \text{km}$, $t = 0.25\ \text{hour}$

Step3: Calculate average speed

$v = \frac{16}{0.25} = 64\ \text{km/hour}$
---

Exercise 3

Step2: Identify given values

$d = 139\ \text{m}$, $v = 13.0\ \text{m/s}$

Step3: Rearrange formula for time

$t = \frac{d}{v}$

Step4: Calculate flight time

$t = \frac{139}{13.0} \approx 10.7\ \text{seconds}$
---

Exercise 4

Step2: Identify given values

$v = 340\ \text{m/s}$, total time $t = 5.2\ \text{s}$

Step3: Find one-way time

One-way time: $t_{one} = \frac{5.2}{2} = 2.6\ \text{s}$

Step4: Calculate canyon depth

$d = v \times t_{one} = 340 \times 2.6 = 884\ \text{m}$
---

Exercise 5

Step2: Identify given values

$d = 6006\ \text{m}$, $t = 4.2\ \text{s}$

Step3: Calculate sound speed in water

$v = \frac{6006}{4.2} = 1430\ \text{m/s}$
---

Answer:

Exercise 2: $64\ \text{km/hour}$
Exercise 3: $\approx 10.7\ \text{seconds}$
Exercise 4: $884\ \text{meters}$
Exercise 5: $1430\ \text{m/s}$

(Note: Exercise 1 text is illegible and cannot be solved with the provided image content.)