Question

1. calculate a driver travels 55 km in 1 hour. he then drives at a speed of 35 km/h for 2 hours. next, he drives 175 km in 3 hours. what was his average speed?

Explanation:

Step1: Calculate total distance

First segment: $55\ \text{km}$
Second segment: $35\ \text{km/h} \times 2\ \text{h} = 70\ \text{km}$
Third segment: $175\ \text{km}$
Total distance: $55 + 70 + 175 = 300\ \text{km}$

Step2: Calculate total time

First segment: $1\ \text{h}$
Second segment: $2\ \text{h}$
Third segment: $3\ \text{h}$
Total time: $1 + 2 + 3 = 6\ \text{h}$

Step3: Compute average speed

Average speed formula: $\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}}$
$\text{Average Speed} = \frac{300}{6} = 50\ \text{km/h}$

• 0-1 min: Elevator moves downward (distance from starting point decreases from 10 to 6 units) at a constant speed.
• 1-2 min: Elevator is stationary (distance remains 6 units).
• 2-3 min: Elevator moves downward again at constant speed, distance drops to 2 units.
• 3-4 min: Elevator is stationary (distance stays at 2 units).
• 4-5 min: Elevator moves slowly downward to 0 units (reaches starting level).

Answer:

$50\ \text{km/h}$

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For question 4 (interpreting the elevator motion graph):