A 1500 kilogram railroad car is moving with a velocity of 4.0 meters per second in a direction that is 20° north of east. In the diagram below, starting from point P, draw a vector that represents the railroad car’s momentum using a scale of 1.0 centimeter = 2.0 x 10^3 kilogram·meter per second.???

Hydrogen and helium are both members of?

Arunner is training for an upcoming marathon by running around a 100-m-diameter circular track at constant speed. let a coordinate system have its origin at the center of the circle with the x-axis pointing east and the y-axis north. the runner starts at (x, y) = (50 m, 0 m) and runs 2.5 times around the track in a clockwise direction.

Convection currents are caused by differences in what two things?