Question

A speed skater averages 11m/s over the first 5s of a race. Find the average speed required over the next 10s to average 12m/s overall

Answer 1

speed = distance/time

distance = speed ×time

distance covered in 5s = 5×11 =55m

let the speed be x over next 10s

distance covered in 10s = 10x m

total distance = 55+10x

total time= 10+5 =15s

overall average speed = 12m/s

55+10x / 15 = 12

55+10x = 180

10x = 125

x = 12.5 m/s

speed over 10s is 12.5 m/s