Math Problem Statement

Select the correct answer. Alisha is driving her car on a straight highway. She drives for 1500 m, then turns around and drives 1000 m back in the opposite direction. The whole journey took 120 s. What was her average velocity, v , to 2 significant figures?

Solution

To calculate the average velocity, we need to use the formula for average velocity:

v=ΔxΔtv = \frac{\Delta x}{\Delta t}

Where:

  • Δx\Delta x is the displacement (the net change in position),
  • Δt\Delta t is the total time taken.

Step 1: Calculate the displacement

Alisha drives 1500 m in one direction, then 1000 m back in the opposite direction. Displacement is the difference between her final and initial positions, so:

Δx=1500m1000m=500m\Delta x = 1500 \, \text{m} - 1000 \, \text{m} = 500 \, \text{m}

Step 2: Total time

The total time given is 120 seconds, so Δt=120s\Delta t = 120 \, \text{s}.

Step 3: Calculate the average velocity

Now, substitute the values into the formula:

v=500m120s=4.1667m/sv = \frac{500 \, \text{m}}{120 \, \text{s}} = 4.1667 \, \text{m/s}

Step 4: Round to two significant figures

Rounding to two significant figures:

v4.2m/sv \approx 4.2 \, \text{m/s}

So, Alisha's average velocity is 4.2 m/s.

Would you like to know more details about this calculation or explore related concepts?

Here are 5 related questions for deeper understanding:

  1. What is the difference between velocity and speed?
  2. How would the average speed differ from the average velocity in this case?
  3. What if the time taken for the return journey was different—how would that affect the average velocity?
  4. How do you calculate average speed given the total distance instead of displacement?
  5. What would the average velocity be if Alisha returned to her starting point?

Tip: Average velocity depends on the displacement, not the total distance traveled.

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Math Problem Analysis

Mathematical Concepts

Kinematics
Average Velocity
Displacement

Formulas

v = Δx / Δt

Theorems

Displacement is the net change in position, which affects average velocity.

Suitable Grade Level

Grades 9-11