Math Problem Statement

A race car traveling at 50 m/s applies its brakes and comes to a complete stop in 7 seconds. Find the acceleration and distance traveled before it stops.

Solution

To solve this problem, we need to find the acceleration and the distance traveled by the race car before it comes to a complete stop.

1. Finding the Acceleration

Acceleration aa can be found using the formula:

a=vfvita = \frac{{v_f - v_i}}{{t}}

Where:

  • vfv_f is the final velocity (0 m/s, since the car stops),
  • viv_i is the initial velocity (50 m/s),
  • tt is the time taken to stop (7 seconds).

Substituting the values:

a=0 m/s50 m/s7 s=50 m/s7 s7.14 m/s2a = \frac{{0 \text{ m/s} - 50 \text{ m/s}}}{{7 \text{ s}}} = \frac{{-50 \text{ m/s}}}{{7 \text{ s}}} \approx -7.14 \text{ m/s}^2

So, the acceleration is approximately 7.14 m/s2-7.14 \text{ m/s}^2.

2. Finding the Distance Traveled

The distance traveled before coming to a stop can be found using the formula:

d=vit+12at2d = v_i \cdot t + \frac{1}{2} a \cdot t^2

Substituting the known values:

d=50 m/s7 s+12(7.14 m/s2)(7 s)2d = 50 \text{ m/s} \cdot 7 \text{ s} + \frac{1}{2} \cdot (-7.14 \text{ m/s}^2) \cdot (7 \text{ s})^2

First, calculate 50 m/s7 s=350 m50 \text{ m/s} \cdot 7 \text{ s} = 350 \text{ m}.

Then, calculate 12(7.14 m/s2)49 s2=175.86 m\frac{1}{2} \cdot (-7.14 \text{ m/s}^2) \cdot 49 \text{ s}^2 = -175.86 \text{ m}.

Now, summing these up:

d=350 m175.86 m=174.14 md = 350 \text{ m} - 175.86 \text{ m} = 174.14 \text{ m}

So, the distance traveled before stopping is approximately 174.14 meters.

Summary:

  • Acceleration: 7.14 m/s2-7.14 \text{ m/s}^2
  • Distance Traveled: 174.14 m174.14 \text{ m}

Would you like to dive deeper into any of these concepts or have any questions?

Here are 5 related questions you might find interesting:

  1. How would the stopping distance change if the initial speed were doubled?
  2. What is the significance of negative acceleration in this context?
  3. How would the stopping time change if the brakes could apply twice the force?
  4. Can you derive the formula for distance traveled from the kinematic equations?
  5. How would the stopping distance differ if the road were inclined?

Tip: Always keep track of the signs when dealing with acceleration, as it indicates the direction of the force applied.

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Math Problem Analysis

Mathematical Concepts

Kinematics
Linear Motion
Acceleration
Distance

Formulas

a = (v_f - v_i) / t
d = v_i * t + (1/2) * a * t^2

Theorems

Kinematic equations of motion

Suitable Grade Level

Grades 9-12