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  • The position of a particle is given by where t is in seconds (b) What is the magnitude,

Q. 4.20 The position of a particle is given by r=3.0t\; \hat{i}-2.0t^{2}\; \hat{j}+4.0\; \hat{k}\; m where  t is in seconds and the coefficients have the proper units for r to be in metres.

(b) What is the magnitude and direction of velocity of the particle at t=2.0\; s ?

Answers (1)

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Put value of time   t  = 2   in the velocity vector as given below : 

                                                                                                v\ =\ 3\; \hat{i}-4t\; \hat{j}

or                                                                                             v\ =\ 3\; \hat{i}-4(2)\; \hat{j}

or                                                                                                   =\ 3\; \hat{i}-8\; \hat{j}

Thus magnitude of velocity is :

                                                                  =\ \sqrt{3^2\ +\ (-8)^2}\ =\ 8.54\ m/s

Direction :  

                                                             \Theta \ =\ \tan^{-1} \frac{8}{3}\ =\ -69.45^{\circ}

Posted by

Devendra Khairwa

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