A 4.5 kg box is being pulled by a girl using a string that makes an angle of 20° horizontal. Find the force of friction if the force exerted on the string is 15 N and the coefficient of friction is 0.5.

Two point charges, separated by 1.5cm, have charge values of +2.0 and-4.0 uc, respectively. what is the value of the mutual force between them

Tornadoes form in unusually violent thunderstorms when there is sufficient (1) instability and (2) wind shear present in the lower atmosphere. elaborate on what does instability mean when discussing the formation of a tornado? a) dry air in the middle atmosphere being rapidly cooled by rain b) winds at all levels of the atmosphere are strong and turn with height c) an isolated strong thunderstorm just ahead of a squall line that merges with the squall line d) very warm, humid conditions in the lower atmosphere; cooler than usual conditions in the upper atmosphere

Agroup of physics students hypothesize that for an experiment they are performing, the speed of an object sliding down an inclined plane will be given by the expression.