Name the device used for measuring weight

Ahot-air balloonist, rising vertically with a constant speed of 5.00 m/s releases a sandbag at the instant the balloon is 40.0 m above the ground. after it is released, the sandbag encounters no appreciable air drag. compute the velocity of the sandbag at 0.250 s after its release.

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

What are two different ways you could find the value of a? explain these methods.