Vectors (11Acd05)

Sheet 05 (Position, Displacement, Velocity & Acceleration Vectors)

  1. The position coordinates of a particle in a plane are \(\left(1, 1\right)\) and \(\left(2, 3\right)\) at time \(t_{1}\) and \(t_{2}\). What are the position vectors of the particle at time \(t_{1}\) and \(t_{2}\)? What is the displacement of the particle during this time interval?

    Ans: \(|\vec{S}|=\sqrt{5}Units\).

  2. The instantaneous coordinate of a particle are \(x=\left(5t-3\right)m\) and \(y=7t^{2}m\). Calculate:
    (i) The average velocity of the particle during time interval from \(t=1s\) to \(t=2s\)?
    (ii) Velocity of the particle at time \(t=2s\).

    Ans: (i) \(\vec{V_{avg}}=\left(5\hat{i}+21\hat{j}\right)\).

  3. If, the position vectors of a particle is given by \(\vec{r}=\left[\left(4Cos2t\right)\hat{i}+\left(4Sin2t\right)\hat{j}+\left(6t\right)\hat{k}\right]m\), then what should be the acceleration of the particle at time \(t=\frac{\pi}{4}sec\)?

    Ans: \(\vec{a_{t=\frac{\pi}{4}}}=-16\hat{j}\frac{m}{s^{2}}\).

  4. A particle starts from origin at time \(t=0sec\), with a velocity \(5.0\hat{i} ms^{-1}\) and moves in X-Y plane with a constant acceleration \(\left(2\hat{i}+3\hat{j}\right) ms^{-2}\). Calculate:
    (i) The time at which X-coordinate of the particle is \(6m\).
    (ii) Y-coordinate of the particle when X-coordinate of the particle is \(6m\).
    (iii) Speed of the particle at that time.

    Ans: (i) \(t=1s\), (ii) \(y=1.5m\) and (iii) \(|\vec{V}|=7.6\frac{m}{s}\).

  5. The position of a particle is given by: \(\vec{r}=\left(2t\hat{i}+3t^{2}\hat{j}+5\hat{k}\right)m\), where \(t\) is measured in seconds, \(\vec{r}\) in meter (m). Calculate:
    (i) Velocity and acceleration of the particle.
    (ii) Magnitude of velocity at time \(t=5s\). and
    (iii) Direction of velocity of the particle at \(t=5s\).

    Ans: (i) \(\vec{V}=\left(2\hat{i}+6t\hat{j}\right)\frac{m}{s}\), & \(\vec{a}=6\hat{j}frac{m}{s^{2}}\) (ii) \(30.07\frac{m}{s}\) and (iii) \(\theta=86^{o}\).

  6. A particle starts from origin at \(t=0\) with a velocity \(\left(5.0\hat{i}\right) ms^{-1}\), and moves in X-Y plane under the action of force which produces a constant acceleration of \(\left(3.0\hat{i}+2.0\hat{j}\right) ms^{-2}\). Calculate:
    (i) Y-coordinate of the particle at the time instant its X-coordinate is \(84m\).
    (ii) What is the speed of the particle at this time?

    Ans: (i) \(Y=36m\) and (ii) \(25.9\frac{m}{s}\).

  7. The position vector of a particle in X-Y plane at \(t= 0\) is given by \(\left(2\hat{i}+4\hat{j}\right)m\). The velocity acquired by the particle in \(2s\) is \(\left(4\hat{i}+3\hat{j}\right) ms^{-1}\). Find: the X and Y coordinate other particle at \(t=2s\).

    Ans: \(X=10m\) and \(Y=10m\).

  8. The position of a particle is given by \(\vec{r}=\left(3t\hat{i}+4t^{3}\hat{j}+5\hat{k}\right)m\). Find:
    (i) The velocity and acceleration of the particle.
    (ii) The magnitude of the velocity and acceleration of the particle at \(t=5Sec\).

    Ans: (i) \(\vec{V}=\left(3\hat{i}+12t^{2}\hat{j}\right)\frac{m}{s}\), \(\vec{a}=24t\hat{j}\frac{m}{s^{2}}\).

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