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The linear velocity of a rotating body i...

The linear velocity of a rotating body is given by `vec(v)=vec(omega)xxvec(r)`, where `vec(omega)` is the angular velocity and `vec(r)` is the radius vector. The angular velocity of a body is `vec(omega)=hat(i)-2hat(j)+2hat(k)` and the radius vector `vec(r)=4hat(j)-3hat(k)`, then `|vec(v)|` is-

A

`sqrt(29)` units

B

`sqrt(31)` units

C

`sqrt(37)` units

D

`sqrt(41)` units

Text Solution

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The correct Answer is:
To solve the problem, we need to calculate the linear velocity vector \(\vec{v}\) using the cross product of the angular velocity vector \(\vec{\omega}\) and the radius vector \(\vec{r}\). Then, we will find the magnitude of the velocity vector. ### Step-by-Step Solution: 1. **Identify the vectors**: - The angular velocity vector is given by: \[ \vec{\omega} = \hat{i} - 2\hat{j} + 2\hat{k} \] - The radius vector is given by: \[ \vec{r} = 4\hat{j} - 3\hat{k} \] 2. **Set up the cross product**: We need to calculate \(\vec{v} = \vec{\omega} \times \vec{r}\). 3. **Write the vectors in determinant form**: To compute the cross product, we can use the determinant of a matrix: \[ \vec{v} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 1 & -2 & 2 \\ 0 & 4 & -3 \end{vmatrix} \] 4. **Calculate the determinant**: Using the determinant formula for a \(3 \times 3\) matrix: \[ \vec{v} = \hat{i} \begin{vmatrix} -2 & 2 \\ 4 & -3 \end{vmatrix} - \hat{j} \begin{vmatrix} 1 & 2 \\ 0 & -3 \end{vmatrix} + \hat{k} \begin{vmatrix} 1 & -2 \\ 0 & 4 \end{vmatrix} \] - Calculate each of the \(2 \times 2\) determinants: - For \(\hat{i}\): \[ \begin{vmatrix} -2 & 2 \\ 4 & -3 \end{vmatrix} = (-2)(-3) - (2)(4) = 6 - 8 = -2 \] - For \(\hat{j}\): \[ \begin{vmatrix} 1 & 2 \\ 0 & -3 \end{vmatrix} = (1)(-3) - (2)(0) = -3 \] - For \(\hat{k}\): \[ \begin{vmatrix} 1 & -2 \\ 0 & 4 \end{vmatrix} = (1)(4) - (-2)(0) = 4 \] 5. **Combine the results**: Now substituting back into the expression for \(\vec{v}\): \[ \vec{v} = -2\hat{i} + 3\hat{j} + 4\hat{k} \] 6. **Find the magnitude of \(\vec{v}\)**: The magnitude of the vector \(\vec{v}\) is given by: \[ |\vec{v}| = \sqrt{(-2)^2 + 3^2 + 4^2} = \sqrt{4 + 9 + 16} = \sqrt{29} \] ### Final Answer: \[ |\vec{v}| = \sqrt{29} \]

To solve the problem, we need to calculate the linear velocity vector \(\vec{v}\) using the cross product of the angular velocity vector \(\vec{\omega}\) and the radius vector \(\vec{r}\). Then, we will find the magnitude of the velocity vector. ### Step-by-Step Solution: 1. **Identify the vectors**: - The angular velocity vector is given by: \[ \vec{\omega} = \hat{i} - 2\hat{j} + 2\hat{k} ...
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Knowledge Check

  • The linear velocity of a particle on a rotating body is given by vec v = vec omega xx vec r" where "vec omega is the angular velocity and vec r is the radius vector. What is the value of |v| if vec omega = hati -2hatj+2hatk and vec r =4hatj-3hatk ?

    A
    `sqrt(23)` units
    B
    `sqrt(29)` units
    C
    `sqrt(35)` units
    D
    `sqrt(47)` units
  • For a body, angular velocity (vec(omega)) = hat(i) - 2hat(j) + 3hat(k) and radius vector (vec(r )) = hat(i) + hat(j) + vec(k) , then its velocity is :

    A
    `-5hat(i) + 2hat(j) + 3hat(k)`
    B
    `-5hat(i) + 2hat(j) - 3hat(k)`
    C
    `-5hat(i) - 2hat(j) + 3hat(k)`
    D
    `-5hat(i) - 2hat(j) - 3hat(k)`
  • If vec(a)=hat(i)+hat(j)+hat(k),vec(a).vec(b)=1andvec(a)xxvec(b)=hat(j)-hat(k), then vec(b) is

    A
    `hat(i)-hat(j)+hat(k)`
    B
    `2hat(j)-hat(k)`
    C
    `hat(i)`
    D
    `2hat(i)`
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