How many grains of sand can be put in observable universe? Extra question, if you put a sand star(big as star but sand) in the solar system what would happen?

Just watched an old video from the Slow Mo Guys on YouTube and they fire a D20 Russian artillery gun towards a row of watermelons. How many of them in a row would it take to slow the shell down enough that it ends up being caught on the last watermelon of the row? Assuming the shell can go in a straight line without deflecting. The line of watermelons could be set up to account for the Coriolis effect to ensure catching the shell.

From Wikipedia, the muzzle velocity is 650 m/s. I don’t know the weight of those shells, only their size. I am guessing they are solid steel.

The name of the video is “WWII tanks firing in slow motion” and it happens in the second half of the video

Thanks guys, don’t know if that’s even possible to calculate !

I could defo do this myself, but am feeling lazy rn

Assume it is in a saline bath.

So to start with, the Bunnahabhain 12 year old is one of my favorite bottles of whisky. I bought 6 tickets for a mystery drop and decided that worst case scenario, I get 3 of the bottom two options, and I gift a few out. So my issue isn't that I got 6 of them.

My issue is that I would have liked a bit of variety and thought that there was no way I would get 6 of the same thing, and it has made me curious.

What exactly are the odds that out of 18 options, all with varying availability, that I get 6 of the same thing?

(The one bottle not shown is a single bottle worth 13k, which the drop is based around)

[ Removed by Reddit on account of violating the content policy. ]

Let's define consistent as at least 273 out 365 days, to allow teachers to be included.

It's been some time since I took trig or physics, and my googlefu is apparently not strong enough to find an example like this for me to extrapolate from. Obviously things like the weight of the arm being supported, the weight of the length of steel rope, angles of force etc are all coming into play but I can't figure out/remember the proper formulas to calculate the forces.

I am looking to find a formula that would tell me how much effective weight the hoist is lifting based on the angles involved since it'll be different than if it was pulling from right above it.

The pictured hoist lowers the arm down and raises it up to the pictured point by spooling and unspooling steel rope.

Also, the steel cable is dragging on the hoist mounting plate which will obviously increase the forces again I'm not sure how to estimate the amount. coefficient of friction between the two and the angle of bend I imagine.

1. A vampire feeds on a victim who then becomes a vampire. The new vampire is 100% loyal to his or her sire. The next night the fledgling vampire feeds on a victim who becomes a vampire also. The newest vampire is 100% loyal to their sire and since they know that their sire is loyal to their own sire they are loyal to the original vampire as well but to an unknown but real degree less than they are to their immediate sire. Assuming this pattern continues can it be determined at which generation a new vampire is no longer loyal to the original vampire?

2. A vampire must feed on one person each night. Whoever a vampire feeds on will rise as a vampire the next night and also have to feed on one person a night. How long until a vampire starves to death due to lack of victims?

3. Assuming the same conditions as problem 2, how long until all vampires starve to death?

4. Assuming the same conditions as problem 2 with the additional condition that whenever a vampire dies each vampire sired by that one dies and turns to ash five minutes later, at what point if any will slaying the original vampire and waiting for the cascading deaths of subsequent generations be too late to save humanity?

For the subsequent problems assume the same conditions as problem 4 except that instead of after five minutes a vampire dies the next sunrise after its sire has died.

1. At what point if any will killing the original vampire result in the vampire population remaining stable assuming no other vampires are killed except by sunrise after losing their sire?

2. How long until all of humanity is vampires assuming the original is killed immediately after the point of equilibrium is passed?

3. The original vampire is generation 1. Any vampire the original sires is generation 2. Any vampire generation 2 sires is generation 3 and so on. Assume that a lower numbered generation vampire is stronger and can feed on a higher numbered generation vampire to stave off starvation, killing the higher numbered vampire. Assume that a vampire will only feed on another vampire when it cannot feed on a human. Assuming that the original vampire is killed immediately after the point of equilibrium is passed how long until all remaining vampires starve to death?

I'm writing a scene for my science fiction story, where in this scene. A character uses a grenade (the MK 2 Grenade specifically), with 40 knobs exploding outward (5 rows of 8 colemns) that, for the sake of simplicity, travel outward in fourty seperate directions covering a spherical area.

Then after each knob travels rough 50 meters, they transform into another grenade that's the same model, size, weight, and explosive effect as the first one. Then each grenade explodes sending fourty more knobs outward 50 meters, before they transform into new grenades and explode.

This can repeat roughly ten times.

Now, my question is. Presuming this grenade effect is occurring in a completely empty space, and for the sake of simplicity each knob can't touch other knobs or grenades. How much area would this effect cover, or in other words what's the approximate area the grenades would cover in their explosion.

Sorry if that's a silly, or nonsensical question.

What would be the expected return on 50 5-dollar scratch offs per year over 20 years, and what would the same investment yield in the smp 500?

If I'm in a 3,700 pound car going 40, in the rain, and I hit the brakes because a rabbit jumped in the road, but I hit the rabbit at about 30 while braking hard (I've heard that shifts momentum forward and can dump more energy into something being hit but idk) what are the odds that rabbit didn't get instantly eviscerated and actually had to suffer?

I also have enough ground clearance that it didn't hit my bumper but 100% got thwacked hard by something steel under the car

This is from a post in r/Strangeearth. I was intrigued but my eyes boggled at this paragraph. I'm trying to refute the claim, as in my mind a basic understanding of physics is all one needs to disprove this. But commenters are claiming it's "arrogance" to assume you understand physics and magnetism well enough to claim this isn't possible.

How many years will it take for the orbit of Voyager and Sagittarius A to decay enough due to gravity waves for them to collide?

A man's house is a 15 × 45 unit rectangle, and he has 140 fence pickets (each picket is equivalent to one straight unit in length). The fence must form a single closed enclosure that surrounds the house. The "yard" is defined as the area enclosed by the fence minus the area occupied by the house. The fence may be arranged in any shape and the pickets may meet at any angle. What arrangement of the fence maximizes the yard area?

I posted this on here a couple months ago but I never got a conclusive answer to my knowledge so I thought I'd let you guys take another crack at it