Question 316212
Let v=10 m/s. The x-axis is time and the y axis is velocity.
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{{{drawing(300,300,-1,10,-2,12,circle(0,10,.2),blue(line(0,10,100,10)),graph(300,300,-1,10,-2,12,0))}}}
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2) In this context, retardation means deceleration or negative acceleration, causing you to reduce your velocity in time. 
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3) {{{drawing(300,300,-1,10,-2,12,circle(0,10,.2),circle(5,10,.2),circle(10,0,.2),blue(line(0,10,5,10)),blue(line(5,10,10,0)),graph(300,300,-1,10,-2,12,0))}}}