**Brain Test**: As you can see the picture, all you have to do is analyze it and tell from the pictured people that who dies if E pushes the stone to the slide on the slope.

This puzzle is sure to boost your cognitive function!

First, you need to keep in mind that the rock will roll down normally despite its crescent shape. Also, keep in mind all the physics and the terrain while you analyze the things.

**Here are the possible answers to this:**

**Answer 1: D and C**

“D” may die first as it clearly appears from the above scene that E has some grudge on D and has planned to kill him. But what if the crescent-shaped stone rolls down and hits the balance under which C is lying? In that case, C may die too (provided the rock is very heavy)!

**Answer 2: D, C and E**

As per the above interpretation if both D and C are killed, then it is highly likely that first stone pushed by “E” hits the balance, thereby, causing other stone on the balance to jump upwards and hit E in the end. So, by pushing down one stone, D, C and E – all three are killed. However, this is possible only if the first rock was heavy enough to fling the big rock on the other side of the seesaw.

**Answer 3: D, C, and B**

It may also happen that the second stone on the balance surge upwards and hits “B” instead of “E”. If this is true, then there will be three casualties – D, C and B. But, this is possible only if the rock is heavy enough!

**Answer 4: Only D**

**Only D and possibly C dies!**

Keep in mind that the crescent rock does not have the same mass as the rock on the seesaw. Despite both rocks having the same diameter, the crescent rock has a huge missing section. Therefore, when E rolls down the crescent rock, it will not have enough mass to fling the big rock on the other side of the seesaw. The only other person who could possibly die is C, but that is only if the crescent rock is heavy enough to lower the seesaw’s plank.

Going by the logic, answer 4 is the correct answer!

Did you guess it right as to who dies if E pushes the stone? Let us know in comments.

ZacThe missing portion of the rock is larg enough for the head and has less mass than the rock below if the rock roll right no one will die

DarleneI love puzzles, and brain teasers!

Brett SalterI assumed A,B,C,D and E. And eventually I will be right.

JulieLol so true!

TonyNo one dies the crescent shape ball misses b and is to light to to crush c

JulieI agree.

CD HI think nobody will die in this diagram. Figure D could squat down in the hole allowing the rolling stone to roll over the hole and end on the one side of the balance. The stone with the cresent cut out of it is likely lighter in weight than the other stone and will not crush Figure C(Assuming both weighted rocks are made from the same material)

Wayne Y AdamsThat so called huge hole in the rolling stone does not reduce the mass as much as you might think. Let’s assume the radius of the stone is 1 unit. The radius of the hole would be 0.5 unit

The volume of a sphere is (4 x pi x r^3)/3 Since everything is constant except the radius we need only look at the cubes of the respective radii. For the stone it will be 1^3 = 1, for the hole it will be 0,5^3 = 0.125. That means the hole only accounts for 12.5% of the mass (and weight) of the stone.

If the stones are large disks, then volume is pi x r^2 x thickness. Now we look at the squares of the respective radii. for the stone it is 1^2 = 1, For the cutout it is 0.5^2 = 0,25. Now we see that the cutout accounts for 25% of the mass.

Another problem with your analysis is the fact that you have the rolling stone coming to a dead stop on the lever. It is probable that the little wedge will serve to launch the rolling stone into the air, since the rolling stone will have a large speed and kinetic energy given the height from which it was rolled. Once it is launched it could kill either A or B. Without actually running the simulation, it looks like A is dead.

A body sliding down a frictionless plane that is launched will reach a height about equal to its starting height (conservation of energy). However, some energy is rotational kinetic energy so the speed of the rolling ball will be less. In addition, even though the inertia of the stationary ball will keep the ramp form moving too far, it will still move and reduce the kinetic energy of the rolling ball, but there is only a unit difference in height between the bottom of the incline and the barrier at the foot of A. Of course we have not taken the angle of launch into account either.

You also have another major error. Given the diameter of the stone and the length of the ramp it will make one complete revolution when it get to D, so the cutout should be straight up on top of the stone not the position you show.

I’m going to go out on a limb and guess none of you are physicists, or you would have considered all these scenarios.

Wayne Y. Adams

B.S. Chemistry (ACS Certified)

M.S. Physics

R&D Chemist (9 yrs.)

Physics Instructor (33 yrs., retired)

Chris AspinwallThank you Mr Adams. I am glad I scrolled and found your answer before asking my question. Although I do not hold the degrees that you do my brain is wired in the same manner, I assume as yours,

when looking at the puzzle. I appreciate the logic put into your answer.

MR ROY S TURNERwhy is the no one option available as “pushing” does not mean moving.

JulieGreat point!

JajjuE ,dies as per Newton’s third law in physicsphysics

Ty TegnerOnly D. Anything more is baseless and unverifiable. For more than D to die, you would have to assume that the crescent-shaped boulder is close in weight or heavier than the full boulder on the other side. That is EXTREMELY unlikely when considering the limited information provided.

PraveshnaD&C

AmarD

Rod PeelNo one dies. D will hear the rumble of the stone and duck his head. There is a small chance that the crescent will coincide with his head but he would be wise to duck anyway. The stone has kinetic energy (1/2 mass x velocity squared ) and will undoubtedly roll to the back of the second stone so the balance will not tip. What a bunch of lucky fellows!

Emmanuella OseiB

LavitaD

BertC B

John sB C

John sC

JEdwD. The distance from E to D is less than the rolling distance circumference meaning the hole is now at the 3 o’clock position when it reaches D.

DeanC and E

SowmyaE

SandraC

todley1No one dies.

The open area on the rolled stone saves D from being killed.

Assuming both stones have the same density, the stone with the open area would not have the necessary weight to catapult the other stone so it stops there and everyone is safe.

jomonC

pujitha gaddaleE only die watch carefully

CatIf one can assume that the lines are indicative of measurements, then clearly no one will die. Both C and D are clearly not touching the bottom of the death trap, which would suggest that both are behind instead of inside. This seems most feasible when you consider the ratio of the sizes of each ‘person’ as well as the probability that this scenario could be a flattened 3D image. It would also be safe to assume that no one would die if the Stone was pushed to the right…

PàrokhanC

Suzanne BaldniE

AslanC and D and possibly B if the trajectory of the Boulder makes it passed the barrier

VigneshAll peoples dies

Jr.Jumsi LoyaC dies first later e himself dies by stone bounds back. And D lastly