The plum pudding model of the atom states that

a) each atom has overall negative charge.
b) each atom has dense, positively charged center.
c) an atom is a solid, invisible sphere that makes up all matter.
d) an atom is made up of electrons in a sea of positive charged.

Which is not a characteristic of a heat pump? a. it is used in air conditioners. b. it uses a refrigerant. c. it requires no work. d. it reverses the normal flow of thermal energy.

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.

Often called simply "velocity," this is the velocity of an object at a particular moment in time.