What is a newton equal to in terms of mass and acceleration

An insulated 40 ft^3 rigid tank contains air at 50 psia and 120°f. a valve connected to the tank is now opened, and air is allowed to escape until the pressure inside drops to 25 psia. the air temperature during this process is kept constant by an electric resistance heater placed in the tank. determine the electrical work done during this process.

When the acceleration of a mass on a spring is zero, the velocity is at a (fill in the blank) . when the velocity of a mass on a spring is zero, the acceleration is at a (fill in the blank) .

Many science fiction movies and tv shows have detected using a nuclear weapon to destroy astroids what problems does plait see with this plan