In order for a train to move on the tracks there must be friction between the and the .

What happens whenever a net force acts on an object

Which of the following is not a symptom of desertification? a) decrease in salt content of the soil b) lowering of the water table c) reduced surface water d) increased soil erosion e) loss of native vegetation

Human genes only differ by less than percent. a. 1 b. 6 c. 11 d. 16