Sam walks to his neighborhood park to play on the swing set. He sits on a swing that is 0.60 meters above the ground and begins swinging. Sam weighs 38 kilograms and is moving at 2.8 meters per second at the bottom of each swing. How much kinetic energy does Sam have at the bottom of each swing? Assume that acceleration due to gravity is 10 m/s2. A. 149 joules B. 228 joules C. 298 joules D. 53 joules

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.