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].
