Math Problem Statement

A particle moves along the curve x = t^5 +15, y= 2t^2 -10 and z=3t+50 where t is the time. Find the components of its velocity and acceleration at t=1 in the direction i+ 2j +2k.

Solution

To solve the problem, we'll first calculate the components of velocity and acceleration in the xx, yy, and zz directions. Then, we'll determine the velocity and acceleration at t=1t = 1. Finally, we'll project these vectors onto the direction vector i+2j+2k\mathbf{i} + 2\mathbf{j} + 2\mathbf{k}.

Step 1: Find the Velocity Components

The velocity vector v(t)\mathbf{v}(t) is the derivative of the position vector r(t)=x(t)i+y(t)j+z(t)k\mathbf{r}(t) = x(t)\mathbf{i} + y(t)\mathbf{j} + z(t)\mathbf{k} with respect to time tt:

Given:

  • x(t)=t5+15x(t) = t^5 + 15
  • y(t)=2t210y(t) = 2t^2 - 10
  • z(t)=3t+50z(t) = 3t + 50

Compute the derivatives:

  • dxdt=vx(t)=5t4\frac{dx}{dt} = v_x(t) = 5t^4
  • dydt=vy(t)=4t\frac{dy}{dt} = v_y(t) = 4t
  • dzdt=vz(t)=3\frac{dz}{dt} = v_z(t) = 3

So, the velocity vector is: v(t)=5t4i+4tj+3k\mathbf{v}(t) = 5t^4 \mathbf{i} + 4t \mathbf{j} + 3 \mathbf{k}

At t=1t = 1: v(1)=5(1)4i+4(1)j+3k=5i+4j+3k\mathbf{v}(1) = 5(1)^4 \mathbf{i} + 4(1) \mathbf{j} + 3 \mathbf{k} = 5\mathbf{i} + 4\mathbf{j} + 3\mathbf{k}

Step 2: Find the Acceleration Components

The acceleration vector a(t)\mathbf{a}(t) is the derivative of the velocity vector v(t)\mathbf{v}(t):

Compute the derivatives:

  • d2xdt2=ax(t)=20t3\frac{d^2x}{dt^2} = a_x(t) = 20t^3
  • d2ydt2=ay(t)=4\frac{d^2y}{dt^2} = a_y(t) = 4
  • d2zdt2=az(t)=0\frac{d^2z}{dt^2} = a_z(t) = 0

So, the acceleration vector is: a(t)=20t3i+4j+0k\mathbf{a}(t) = 20t^3 \mathbf{i} + 4 \mathbf{j} + 0 \mathbf{k}

At t=1t = 1: a(1)=20(1)3i+4j+0k=20i+4j+0k\mathbf{a}(1) = 20(1)^3 \mathbf{i} + 4 \mathbf{j} + 0 \mathbf{k} = 20\mathbf{i} + 4\mathbf{j} + 0\mathbf{k}

Step 3: Direction Vector and Normalization

Given direction vector: d=i+2j+2k\mathbf{d} = \mathbf{i} + 2\mathbf{j} + 2\mathbf{k}

Normalize the direction vector: d=12+22+22=1+4+4=9=3|\mathbf{d}| = \sqrt{1^2 + 2^2 + 2^2} = \sqrt{1 + 4 + 4} = \sqrt{9} = 3 d^=13(i+2j+2k)\hat{\mathbf{d}} = \frac{1}{3} (\mathbf{i} + 2\mathbf{j} + 2\mathbf{k})

Step 4: Project Velocity and Acceleration onto the Direction Vector

  • Velocity projection: Velocity in direction of d=v(1)d^=(5i+4j+3k)13(i+2j+2k)\text{Velocity in direction of } \mathbf{d} = \mathbf{v}(1) \cdot \hat{\mathbf{d}} = (5\mathbf{i} + 4\mathbf{j} + 3\mathbf{k}) \cdot \frac{1}{3}(\mathbf{i} + 2\mathbf{j} + 2\mathbf{k}) =13(5(1)+4(2)+3(2))=13(5+8+6)=193= \frac{1}{3} (5(1) + 4(2) + 3(2)) = \frac{1}{3} (5 + 8 + 6) = \frac{19}{3}

  • Acceleration projection: Acceleration in direction of d=a(1)d^=(20i+4j)13(i+2j+2k)\text{Acceleration in direction of } \mathbf{d} = \mathbf{a}(1) \cdot \hat{\mathbf{d}} = (20\mathbf{i} + 4\mathbf{j}) \cdot \frac{1}{3} (\mathbf{i} + 2\mathbf{j} + 2\mathbf{k}) =13(20(1)+4(2)+0(2))=13(20+8)=283= \frac{1}{3} (20(1) + 4(2) + 0(2)) = \frac{1}{3} (20 + 8) = \frac{28}{3}

Final Results:

  • Velocity component in the direction i+2j+2k\mathbf{i} + 2\mathbf{j} + 2\mathbf{k} at t=1t = 1: 193\frac{19}{3} units.
  • Acceleration component in the direction i+2j+2k\mathbf{i} + 2\mathbf{j} + 2\mathbf{k} at t=1t = 1: 283\frac{28}{3} units.

Would you like more details or have any questions? Here are some related questions to expand your understanding:

  1. How do you calculate the magnitude of a vector?
  2. What is the physical significance of projecting a vector onto another vector?
  3. How does the velocity vector change as the parameter tt increases?
  4. What is the geometric interpretation of a direction vector?
  5. How can you use vectors to describe motion in three-dimensional space?

Tip: When dealing with vector projections, always ensure the direction vector is normalized to maintain accurate component calculations.

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Math Problem Analysis

Mathematical Concepts

Vector calculus
Parametric equations
Velocity and acceleration vectors
Vector projection

Formulas

Velocity vector formula
Acceleration vector formula
Vector projection formula

Theorems

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Suitable Grade Level

Advanced High School