Two objects, =15.3 kg and m=5.21 kg are connected with an ideal string and suspended by a pulley. the pulley rotates with no friction, but has significant mass. the pulley is in the shape of a uniform disk with radius =7.5 cm and mass =14.1 kg. the string causes the pulley to rotate without slipping. if the masses are started from rest and allowed to move ℎ=2.5 m.

Achemistry student needs of 40ml diethylamine for an experiment. by consulting the crc handbook of chemistry and physics, the student discovers that the density of diethylamine is 0.7 . calculate the mass of diethylamine the student should weigh out. round your answer to significant digits.

The dipole moment of the water molecule (h2o) is 6.17x10^-30 c.m. consider a water molecule located at the origin whose dipole moment p points in the +x-direction. a chlorine ion ( of charge-1.60x10^-19c , is located at x=3.00x10^-9m . assume that is much larger than the separation d between the charges in the dipole, so that the approximate expression for the electric field along the dipole axis can be used. a) find the magnitude of the electric force that the water molecule exerts on the chlorine ion. b) what is the direction of the electric force. -x-direction or +x-direction c) is this force attractive or repulsive?

What practical value did astronomy offer to ancient civilizations?