Exam 3: Motion in Two Dimensions

At t = 0,a particle leaves the origin with a velocity of 12 m/s in the positive x direction and moves in the xy plane with a constant acceleration of $( - 2.0 \tilde { \mathbf { i } } + 4.0 \tilde { \mathbf { j } } ) \mathrm { m } / \mathrm { s } ^ { 2 }$ .At the instant the y coordinate of the particle is 18 m,what is the x coordinate of the particle?

A particle moves at a constant speed in a circular path with a radius of 2.06 cm.If the particle makes four revolutions each second,what is the magnitude of its acceleration?