Afootball coach starts at the 35-yard line (a) and walks to the 15-yard line (b). he turns around and walks to the 40-yard line (c). he turns around again and walks back to the 0-yard line (d). he turns around once more and walks back to the 25-yard line (e), thus completing his 10 minutes of pacing.

a) A football coach starts at the 35-yard line and walks to the 15-yard line.

So, the first amount of displacement covered is calculated as below.

Displacement = final point-initial point

D1 = 35 - 15 = 20 yards.

b. He turns around and walks to the 40-yard line.

Coach starts from the 15-yard line and walks to the 40-yard line, so his displacement is calculated as below

D2 = 40 - 15 = 25 yards.

3. He turns around again and walks back to the 0-yard line.

Coach starts from the 40-yard line and walks to the 0-yard line, so his displacement is calculated as below

D3 = 40 - 0 = 40 yards.

4. He turns around one more and walks back to the 25-yard line.

Coach starts from the 0-yard line and walks to the 25-yard line, so his displacement is calculated as below

D4 = 0 + 25 = 25 yards.

The total distance walked is

D = D1 + D2 + D3 + D4 = 20 + 25 + 40 + 25 = 110 yards.

Hence average speed of the coach is

Spee = 110[yards]/10[min] = 11 [yards/min].