Math Problem Statement

True or false: If a ball is dropped from the upper observation deck of the CN Tower, 450 m above the ground, then the average velocity over the time interval that starts t = 0 and ends at t = 5 is given by lim (h→0) [(4.9(5+h)^2 - 4.9(5)^2) / h]. You can assume the distance the object has fallen is given by s = f(t) = 4.9t^2. Justify your answer.

Solution

The question asks whether the average velocity of a ball dropped from the CN Tower (450 meters above the ground) over a time interval starting at t=0t = 0 and ending at t=5t = 5 seconds is given by the following limit expression:

limh04.9(5+h)24.9(5)2h\lim_{h \to 0} \frac{4.9(5+h)^2 - 4.9(5)^2}{h}

Problem Breakdown:

  1. Distance Function: The distance fallen by the ball as a function of time tt is given by the equation s=f(t)=4.9t2s = f(t) = 4.9t^2. This comes from the equation of motion for free-fall under gravity (where 9.8m/s29.8 \, \text{m/s}^2 is the acceleration due to gravity, and dividing by 2 gives 4.94.9).

  2. Average Velocity Over Time Interval: The average velocity over a time interval [0,5][0, 5] is the change in distance divided by the change in time: Average velocity=f(5)f(0)50\text{Average velocity} = \frac{f(5) - f(0)}{5 - 0} where f(t)=4.9t2f(t) = 4.9t^2.

    Substituting into the above formula: Average velocity=4.9(5)24.9(0)250=4.9(25)5=24.5m/s\text{Average velocity} = \frac{4.9(5)^2 - 4.9(0)^2}{5 - 0} = \frac{4.9(25)}{5} = 24.5 \, \text{m/s}

  3. Limit Expression: The limit provided in the problem, limh04.9(5+h)24.9(5)2h,\lim_{h \to 0} \frac{4.9(5+h)^2 - 4.9(5)^2}{h}, is a form of the derivative of the function f(t)=4.9t2f(t) = 4.9t^2 at t=5t = 5. This limit calculates the instantaneous velocity at t=5t = 5, not the average velocity over the interval. Let’s compute the derivative.

  4. Instantaneous Velocity: The derivative of s=4.9t2s = 4.9t^2 with respect to tt gives the instantaneous velocity: v(t)=ddt[4.9t2]=9.8t.v(t) = \frac{d}{dt}[4.9t^2] = 9.8t. At t=5t = 5, v(5)=9.8(5)=49m/s.v(5) = 9.8(5) = 49 \, \text{m/s}.

Conclusion:

The limit provided in the question is not the average velocity but the instantaneous velocity at t=5t = 5, which is 49 m/s. The correct average velocity over the interval [0,5][0, 5] is 24.5 m/s.

Thus, the statement is false.

Would you like further details or have any questions?

Related Questions:

  1. How is the equation s=4.9t2s = 4.9t^2 derived for a free-falling object?
  2. What is the difference between average velocity and instantaneous velocity?
  3. How do you compute the derivative of a quadratic function?
  4. What is the significance of the limit definition of a derivative?
  5. How does gravity affect the velocity of an object in free fall?

Tip: The derivative provides the slope of the tangent line to the curve, which represents instantaneous velocity at a given time.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Instantaneous Velocity
Average Velocity

Formulas

Average Velocity = (f(5) - f(0)) / (5 - 0)
Derivative of s = 4.9t^2 with respect to t
Instantaneous velocity = lim (h→0) [(4.9(5+h)^2 - 4.9(5)^2) / h]

Theorems

Limit definition of derivative
Equations of motion under constant acceleration

Suitable Grade Level

College Level (Introductory Calculus)