Math Problem Statement

The position of a particular particle as a function of time is given by r⃗ = ( 9.60t⋅i^

  • 8.85j^
  • 1.00t2⋅k^ )m , where t is in seconds.What is the average velocity of the particle between t =1.00 s and t =3.00 s ? Express your answer in terms of the unit vectors i^ , j^ , and k^ .

Solution

To find the average velocity of the particle between t=1.00st = 1.00 \, \text{s} and t=3.00st = 3.00 \, \text{s}, we first need to determine the position vector r(t)\vec{r}(t) at these two times and then use the formula for average velocity.

Given Position Vector

The position of the particle as a function of time is given by: r(t)=(9.60ti^+8.85j^1.00t2k^)m\vec{r}(t) = (9.60t \, \hat{i} + 8.85 \, \hat{j} - 1.00t^2 \, \hat{k}) \, \text{m}

Step 1: Calculate the position vector at t=1.00st = 1.00 \, \text{s}

r(1.00)=(9.60(1.00)i^+8.85j^1.00(1.00)2k^)m\vec{r}(1.00) = (9.60(1.00) \, \hat{i} + 8.85 \, \hat{j} - 1.00(1.00)^2 \, \hat{k}) \, \text{m} r(1.00)=(9.60i^+8.85j^1.00k^)m\vec{r}(1.00) = (9.60 \, \hat{i} + 8.85 \, \hat{j} - 1.00 \, \hat{k}) \, \text{m}

Step 2: Calculate the position vector at t=3.00st = 3.00 \, \text{s}

r(3.00)=(9.60(3.00)i^+8.85j^1.00(3.00)2k^)m\vec{r}(3.00) = (9.60(3.00) \, \hat{i} + 8.85 \, \hat{j} - 1.00(3.00)^2 \, \hat{k}) \, \text{m} r(3.00)=(28.80i^+8.85j^9.00k^)m\vec{r}(3.00) = (28.80 \, \hat{i} + 8.85 \, \hat{j} - 9.00 \, \hat{k}) \, \text{m}

Step 3: Compute the displacement vector Δr\Delta \vec{r}

The displacement vector is given by: Δr=r(3.00)r(1.00)\Delta \vec{r} = \vec{r}(3.00) - \vec{r}(1.00) Δr=(28.80i^+8.85j^9.00k^)(9.60i^+8.85j^1.00k^)\Delta \vec{r} = (28.80 \, \hat{i} + 8.85 \, \hat{j} - 9.00 \, \hat{k}) - (9.60 \, \hat{i} + 8.85 \, \hat{j} - 1.00 \, \hat{k}) Δr=(28.809.60)i^+(8.858.85)j^+(9.00+1.00)k^\Delta \vec{r} = (28.80 - 9.60) \, \hat{i} + (8.85 - 8.85) \, \hat{j} + (-9.00 + 1.00) \, \hat{k} Δr=(19.20i^+0j^8.00k^)m\Delta \vec{r} = (19.20 \, \hat{i} + 0 \, \hat{j} - 8.00 \, \hat{k}) \, \text{m}

Step 4: Calculate the average velocity vavg\vec{v}_{\text{avg}}

The average velocity is given by: vavg=ΔrΔt\vec{v}_{\text{avg}} = \frac{\Delta \vec{r}}{\Delta t} where Δt=3.00s1.00s=2.00s\Delta t = 3.00 \, \text{s} - 1.00 \, \text{s} = 2.00 \, \text{s}.

vavg=(19.20i^+0j^8.00k^)2.00m/s\vec{v}_{\text{avg}} = \frac{(19.20 \, \hat{i} + 0 \, \hat{j} - 8.00 \, \hat{k})}{2.00} \, \text{m/s} vavg=(9.60i^+0j^4.00k^)m/s\vec{v}_{\text{avg}} = (9.60 \, \hat{i} + 0 \, \hat{j} - 4.00 \, \hat{k}) \, \text{m/s}

Final Answer

The average velocity of the particle between t=1.00st = 1.00 \, \text{s} and t=3.00st = 3.00 \, \text{s} is: vavg=9.60i^4.00k^m/s\vec{v}_{\text{avg}} = 9.60 \, \hat{i} - 4.00 \, \hat{k} \, \text{m/s}

Would you like further details or have any questions about this problem? Here are some related questions:

  1. How would you determine the instantaneous velocity at t=2.00st = 2.00 \, \text{s}?
  2. What would be the particle's displacement vector from t=0st = 0 \, \text{s} to t=4.00st = 4.00 \, \text{s}?
  3. How does the position vector change if the coefficient of t2t^2 in the k^\hat{k} direction were doubled?
  4. What is the significance of the j^\hat{j} component being constant in this problem?
  5. How would the average speed differ from the average velocity in this case?

Tip: When dealing with vectors, remember that each component of the vector should be treated independently in calculations like addition, subtraction, and differentiation.

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Math Problem Analysis

Mathematical Concepts

Calculus
Kinematics
Vectors

Formulas

Average Velocity = Δr / Δt
Position Vector r(t) = (9.60t ⋅ i^ + 8.85 ⋅ j^ - 1.00t^2 ⋅ k^)
Displacement Vector Δr = r(t2) - r(t1)

Theorems

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Suitable Grade Level

Grades 11-12 or College Level