Asprinter is advised to reduced his speed slowly after completing his race. why

The sprinter is advised to reduce his speed slowly after completing the race because of the power that is needed when the stoppage is down in a faster manner could be very great. This would translate to the great usage in gasoline. Also, the inertia of the vehicle is quiet high so it is hard to stop it very suddenly. 

you cant move and you feel like someones pushing you down onto your bed it can feel like you want to get up but you just can't it can be extremely scary

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.