Recent content by Jean-Louis

Homework Statement To solve the following equation 3x^3 + x^2 + 15x + 27 = 0 Homework Equations The Attempt at a Solution {(x-> 1/9{-1 - 134/(-3079+27Sqrt.(16305)^(1/2) + (-3079+27Sqrt.(16305)^(1/3)} {x-> -1/9 + 67(1+iSqrt.3)/9(-3079+27Sqrt.(16305)^(1/2) -1/18...

I have a copper coin with a hole in the centre. The hole is a circle. If the coin is heated, the metal will expand towards all directions in and out, so the radius of the circle will be decreased. Correct?

if L means angular momentum. L(no moon) = L(earth+moon) + L(moon) + L(moon's orbit) If we toss in L=Iw, hence we can figure out how fast Earth would be spinning. The Barycentre Eart-Moon system will change, the new barycentre will be at the centre of mass of the Earth.

Angular momentum is what physicists call for the Earth-Moon system zero-sum game. Currently, the Moon's distance from the Earth is increasing by about 3 centimeters per year. Since the Earth's angular momentum is decreasing, the Moon's angular momentum must increase to keep the overall angular...

Would Earth spin much faster without its orbiting moon ? The pull of the moon, puts the brakes on Earth's daily rotation, right ? Is there a way to calculate how fast the Earth would be spinning on its axis, If we didn't have the moon ?

Earth's velocity is 30 km/s. What would be Earth's velocity without the moon ? What's the formula?

Imagine that you are on the surface of the moon, playing golf. So, is it possible to hit a golf ball on the surface of the moon and have it achieve a stable orbit around the moon?

I need help expanding the expression I posted.

It is asked to expand the expression

N.B. i can't type the symbol for vector, so instead i will just type vect. So, how can you solve: |R - (vect.R' - vect.a)/|vect.R - vect.a| | the term (vect.R' - vect.a)/|vect.R - vect.a| is less than one due to physics.

I think I got it. Here it goes : sin(x/2) = +/- sqrt((1-cos(x))/2) and sin^2(z) = 1 - cos^2(x) so that that (sinA)^2 + (sinB)^2 + (sinC)^2 = 3 - (cos^2(A) + cos^2(B) + cos^2(C)) Now (sin A/2 + sin B/2 + sin C/2)^2 = (+/- sqrt((1-cos(A))/2) + +/- sqrt((1-cos(B))/2) + +/-...

Show that : (sinA/2 + sinB/2 + sinC/2)^2 >= (sinA)^2 + (sinB)^2 + (sinC)^2 A,B and C are the angles of a triangle.

Thanks for your feedback. This is not homework. I have an aquarium, and I wanted a mathematical approach. I think I founded. I was told that this not a calculus problem, since the water is not continuously changing. So the approach is algebraic. Sorry if I caused any inconvenience. (if you...

How to devise a usefull formula for aquarium water changes. I have a 50g tank (not including substrate and animals). I want to do daily water changes so that at the end of 6 months I will have replaced 95% of the water present at the beginning of the water change regimen. I want to replace...