$36.$ In a small drop forge, a machine part is forged. The hammer weighs $400$ lb and is dropped from a height of $5$ ft $.$ Determine the initial impulse exerted on the machine part assuming that the $1000$ lb anvil is $($a$)$ resting directly on the hard ground $($final velocity is zero$)$ and $($b$)$ supported by springs $($anvil and hammer travel together$).$