Question

work each of the following problems. show all work.

1. a car travels a distance of 100 km in 2 hours. what is the average speed of the car (km/h)?
2. an nfl wide receiver prospect runs 40 m in 4.5 seconds. what is the average speed of the wide receiver (m/s)?
3. the average human walks at a speed of 5 km per hour. if your pe teacher asks you to walk for 30 minutes in gym class, how far would you walk (km)?
4. the posted speed limit on the road heading from your house to school is 45 mi/h, which is about 20 m/s. if you live 8 km (8,000 m) from school, how long will it take you to get to school if there is no traffic? convert your answer to minutes.

questions continued on next page
unit iii practice problems
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Explanation:

Problem 1:

Step1: Recall speed formula

The formula for average speed \( s \) is \( s=\frac{d}{t} \), where \( d \) is distance and \( t \) is time.

Step2: Substitute values

Given \( d = 100\space km \) and \( t = 2\space hours \), substitute into the formula: \( s=\frac{100}{2} \)

Step3: Calculate

\( \frac{100}{2}=50 \)

Step1: Recall speed formula

\( s=\frac{d}{t} \), with \( d = 40\space m \), \( t = 4.5\space s \)

Step2: Substitute and calculate

\( s=\frac{40}{4.5}\approx8.89 \)

Step1: Convert time to hours

30 minutes \(=\frac{30}{60} = 0.5\space hours \)

Step2: Use distance formula \( d = s\times t \)

Given \( s = 5\space km/h \), \( t = 0.5\space h \), so \( d=5\times0.5 \)

Step3: Calculate

\( 5\times0.5 = 2.5 \)

Answer:

\( 50\space km/h \)

Problem 2: