This will blow u r brains How do we know that we don't live in a box and the stars are just poked in holes so we can breathe and that the holes were poked in patterns so that the early astronomers didn't get bored. ALSO what if the sun is just a big flashlight and the moon is a big glow stick in a ball And what is the pictures of space are just drawings i mean we have good drawers in this box. AND how do we know that the video of the first man on the moon wasn't on a green screen

Aboy with a mass 25 kg climbs into a small tree. he sits on a branch that is 2.o m above to the ground. what is his gravitational potential energy above the ground?

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.