many many things, Loose lug nuts which lets wheel make knocking noise. Engine will make a knocking noise if it is really low on oil. Some timing belts make a knocking, slapping noise just before they break.These are just a few examples . Have someone ride in car with you as you duplcate the noise and see if they can determine which part of the vehicle it is coming from.
You forgot to let your wife in
It's really hard to understand what you're asking here."What causes a knocking sound when your car drops into a hole while driving?"If that's your question, I imagine that it would be the sound of your car dropping into a hole.
Gearbox oil needs changing.
Bad CV joint, loose rim, Loose caliper
If it only happens when backing up, you may have the parking brake engaged.
The combination of fuel still being pumped into the engine and air
Driving at 50mph or above what causes a loud knocking clicking sound during acceleration?
Check the drive axle for a broken and leaking boot or bad CV joint.
You need to get your car checked.
a dog
Mine did the same, mine was a motor mount.
counterbalancer is bad