Answer:
External force on him will be 112 N
Explanation:
We have given the mass of the sprinter m =70 kg
Acceleration of the sprinter 
We have to find the net external force
According to second law of motion force = mass ×acceleration
Force is dependent on the mass and acceleration
So 
So external force will be 112 N
4% of 110 is 4.4. So the possible range of speeds is the interval from 110-4.4 till 110+4.4.
105.6 till 114.4
Answer:
a. lower surface area, less resistence
b. more surface area, the load is split so no single tire overstrained
c. more surface area, more resistance against the sand. human steps sink down in the sand.
d. rapid change in air pressure on eardrums lead to somewhat-painful tension
e. air would always find its way in so no pressure difference can be achieved
(would indeed appreciate the brainliest if you appreciate the work)