Math Problem Statement

Suppose an arrow is shot upward on the moon with a velocity of 44 m/s, then its height in meters after seconds is given by h(t)=44t-0.83t^2 . Find the average velocity over the given time intervals.

[8, 9]:

[8, 8.5]:

[8, 8.1]:

[8, 8.01]:

[8, 8.001]:

Solution

To find the average velocity of the arrow over the specified time intervals, we use the formula for average velocity:

Average velocity=h(t2)h(t1)t2t1\text{Average velocity} = \frac{h(t_2) - h(t_1)}{t_2 - t_1}

where t1t_1 is the initial time and t2t_2 is the final time. Here, h(t)=44t0.83t2h(t) = 44t - 0.83t^2 is the height function.

We will now calculate the average velocity over each of the given intervals.

Interval [8, 9]:

  • t1=8t_1 = 8, t2=9t_2 = 9

Average velocity=h(9)h(8)98\text{Average velocity} = \frac{h(9) - h(8)}{9 - 8}

First, calculate h(9)h(9) and h(8)h(8):

h(9)=44(9)0.83(9)2=39667.23=328.77h(9) = 44(9) - 0.83(9)^2 = 396 - 67.23 = 328.77 h(8)=44(8)0.83(8)2=35253.12=298.88h(8) = 44(8) - 0.83(8)^2 = 352 - 53.12 = 298.88

Average velocity=328.77298.881=29.89m/s\text{Average velocity} = \frac{328.77 - 298.88}{1} = 29.89 \, \text{m/s}

Interval [8, 8.5]:

  • t1=8t_1 = 8, t2=8.5t_2 = 8.5

Average velocity=h(8.5)h(8)8.58\text{Average velocity} = \frac{h(8.5) - h(8)}{8.5 - 8}

Calculate h(8.5)h(8.5):

h(8.5)=44(8.5)0.83(8.5)2=37460.07625=313.92375h(8.5) = 44(8.5) - 0.83(8.5)^2 = 374 - 60.07625 = 313.92375

Average velocity=313.92375298.880.5=15.043750.5=30.0875m/s\text{Average velocity} = \frac{313.92375 - 298.88}{0.5} = \frac{15.04375}{0.5} = 30.0875 \, \text{m/s}

Interval [8, 8.1]:

  • t1=8t_1 = 8, t2=8.1t_2 = 8.1

Average velocity=h(8.1)h(8)8.18\text{Average velocity} = \frac{h(8.1) - h(8)}{8.1 - 8}

Calculate h(8.1)h(8.1):

h(8.1)=44(8.1)0.83(8.1)2=356.454.47283=301.92717h(8.1) = 44(8.1) - 0.83(8.1)^2 = 356.4 - 54.47283 = 301.92717

Average velocity=301.92717298.880.1=3.047170.1=30.4717m/s\text{Average velocity} = \frac{301.92717 - 298.88}{0.1} = \frac{3.04717}{0.1} = 30.4717 \, \text{m/s}

Interval [8, 8.01]:

  • t1=8t_1 = 8, t2=8.01t_2 = 8.01

Average velocity=h(8.01)h(8)8.018\text{Average velocity} = \frac{h(8.01) - h(8)}{8.01 - 8}

Calculate h(8.01)h(8.01):

h(8.01)=44(8.01)0.83(8.01)2=352.4453.1846603=299.2553397h(8.01) = 44(8.01) - 0.83(8.01)^2 = 352.44 - 53.1846603 = 299.2553397

Average velocity=299.2553397298.880.01=0.37533970.01=37.53397m/s\text{Average velocity} = \frac{299.2553397 - 298.88}{0.01} = \frac{0.3753397}{0.01} = 37.53397 \, \text{m/s}

Interval [8, 8.001]:

  • t1=8t_1 = 8, t2=8.001t_2 = 8.001

Average velocity=h(8.001)h(8)8.0018\text{Average velocity} = \frac{h(8.001) - h(8)}{8.001 - 8}

Calculate h(8.001)h(8.001):

h(8.001)=44(8.001)0.83(8.001)2=352.04453.1278477=298.9161523h(8.001) = 44(8.001) - 0.83(8.001)^2 = 352.044 - 53.1278477 = 298.9161523

Average velocity=298.9161523298.880.001=0.03615230.001=36.1523m/s\text{Average velocity} = \frac{298.9161523 - 298.88}{0.001} = \frac{0.0361523}{0.001} = 36.1523 \, \text{m/s}

Summary of Average Velocities:

  1. Interval [8, 9]: 29.89m/s29.89 \, \text{m/s}
  2. Interval [8, 8.5]: 30.0875m/s30.0875 \, \text{m/s}
  3. Interval [8, 8.1]: 30.4717m/s30.4717 \, \text{m/s}
  4. Interval [8, 8.01]: 37.53397m/s37.53397 \, \text{m/s}
  5. Interval [8, 8.001]: 36.1523m/s36.1523 \, \text{m/s}

Would you like more details on any of the steps?

Related questions:

  1. How do we calculate instantaneous velocity using limits?
  2. What is the significance of smaller time intervals in average velocity?
  3. How does the acceleration on the moon affect the motion of the arrow?
  4. Can we use a different method to find the average velocity?
  5. What happens to velocity as the arrow approaches its peak height?

Tip:

The closer the time intervals are, the more the average velocity approximates the instantaneous velocity.

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Math Problem Analysis

Mathematical Concepts

Average Velocity
Quadratic Functions
Algebra

Formulas

Average velocity = (h(t2) - h(t1)) / (t2 - t1)
Quadratic equation: h(t) = 44t - 0.83t^2

Theorems

None explicitly, but uses the concept of average velocity from kinematics

Suitable Grade Level

Grades 9-12