Question

Help plsss i need #1

Answer 1

Speed is  (distance covered) divided by (time to cover the distance).

"Faster" means he covered more distance in less time.

On a graph of distance/time, the speed is the slope of the line,
because the slope of the line is just

                       (change in distance) divided by (change in time) .

In 'A', the runner went to the middle of the track (20 yards)
before the race started.  Then, when the coach fired the pistol,
he took 4 seconds to run the last half of the track. 
The slope is (20 yards) / (4 seconds)  =  5 yards per second.

In 'B', the runner started at the starting line (zero distance), and when the
race started, he ran 30 yards in 4 seconds.
The slope is (30 yards) / (4 seconds)  =  7.5 yards per second.

In 'C', the distance doesn't change at all.  The runner went to the 40-yards
place before anybody started running, and just stayed there.
The slope is (zero) / (4 seconds).  That's zero yards per second. 
The runner is not running at all.  He's just standing there, watching
the other runners run toward him.

In 'D', the runner went to the 20-yard mark before the race started,
just like 'A' did.  When the pistol fired and the clock started, 'A' and 'D'
were both standing there, and started running.
'D' only ran 10 yards in the whole 4 seconds.
'B' got there at the same time that 'D' did, but 'B' ran 40 yards,
and 'D' only ran 10 yards.
The slope of 'D' is (10 yards) / (4 seconds)  =  2.5 yards per second.
 
Graph 'B' is the steepest line, and that means the fastest speed.