[size=150][b]A particle moves along a straight line and passes through a fixed point [i]O[/i]. Its acceleration, [i]a[/i] ms[sup]-2[/sup], at [i]t[/i] seconds after passing through [i]O [/i]is given by [/b][/size][size=150][math]a=4-2t[/math][b].[/b][/size][br][size=150][b](a) Find the initial acceleration, in of ms[sup]-2 [/sup]the particle when [/b][math]t=3[/math][b].[/b][/size]

[b][size=150](b) Determine the range of time, in seconds, when the velocity of the particle is decreasing.[/size][/b]