[Other] Xavier’s math checks out
https://redd.it/1vx4e7e
@TheyDidTheMath

[Request] How much weight are you actually lifting on the pull-down side? Assume 80kg person using it.
https://redd.it/1vx5761
@TheyDidTheMath

[Request] Presuming this was for a 200-pound, six-foot male. How much time would it take for the hourglass to empty?
https://redd.it/1vx7wrh
@TheyDidTheMath

[request] Why Won’t My Foam Wrap?

https://redd.it/1vx9odb
@TheyDidTheMath

[Request] Disregarding the compression to upload, at 8gbps, can mumbo actually upload raw 32k streams?

https://redd.it/1vxfmez
@TheyDidTheMath

[Request] What’s the formal proof that 3 < 10?
https://redd.it/1vxiywp
@TheyDidTheMath

[Request] What is the shortest flight time possible (with timezones)
https://redd.it/1vxje8m
@TheyDidTheMath

[Request] A disease affects 1% of people. With a 99% sensitive and 99% specific test, what is the exact probability a positive test means you are actually sick?
/r/VouchPick/comments/1vwrw77/a_test_has_99_sensitivity_and_99_specificity_you/

https://redd.it/1vxfs6b
@TheyDidTheMath

[Request] Could this be done?
https://redd.it/1vxmx7d
@TheyDidTheMath

[Request] approximately how many Roman soldiers in this painting?
https://redd.it/1vxs629
@TheyDidTheMath

[Request] Why does this circle approximation still give 4 instead of pi?
https://redd.it/1vxtynk
@TheyDidTheMath

Self Which travels faster? Air molecule or a bullet?

(Is it the right way to do it?)

The higher the temperature the faster molecules travel. In fact temperature can be defined by how fast molecules move. It's called thermal velocity.

Assuming a bullet is shot at 500m/s - 1300m/s, at which temperature does the air move faster? For air, we need to account for it being a mixture of nitrogen and oxygen.

Here is the equation for the speed in 3D space: v = √(8(K_B T)/m).

k_B is Bolzmann constant

T is the temperature in Kelvin.

m is the mean mass of an air particle.

We are looking for a T that gives v = 1300m/s.

K_B = 1.380649 e\^-23 K\^-1 J
m = n1*m_N2 + n2*m_O2 = [0.78*(2*14) 0.21*(2*16)\] * 1.672 e\^-27 kg = 4.777 e\^-26 kg

T = mv\^2 / 8 K_B = (4.777 e\^-26 [kg\]) 1300\^2 [m\^2/s\^2\]/ 8 1.380649 e\^-23 [K\^-1 J\] = 731 K = 458°C
For v =500 m/s, T = 108 K = -165°C.

Therefore air particles in room temperature on average are in the range but not as fast as the fastest bullets.

https://redd.it/1vxvozd
@TheyDidTheMath

[Request] how fast is the cannonball moving and how much force does it strike Frank with?

https://redd.it/1vxwby5
@TheyDidTheMath

[Request] What is the minimum temperature of this oven?
https://redd.it/1vxyu3m
@TheyDidTheMath