John b. watson and b. f. skinner were the principal contributors to the behavioral perspective.

John Watson

Believed that psychology should ONLY study what can be observed and measured and that behavior can be molded by the environment we live in.

B.F. Skinner

Believed "No such thing as free will".
 
 Both John B. Watson and BF Skinner were main contributors in the world of psychology in a behavioral approach. John B. Watson was the one who created the school of behaviorism. He studied behaviors and made a lot research on human and animal behavior and advertising. BF Skinner, on the other hand, was the one who started reinforcements and conditioning. He believed that behaviors are highly influenced by the consequences of the act. 

 Hope this helps. 

Examples: mental health problems cardiovascular disease obesity and other eating disordersmenstrual problems skin and hair problems

    m₁v₁ + m₂v₂ = (m₁ + m₂)vmomentum is conserved.the left-hand side of the equation represents the momentum in the system before the collision.the right-hand side represents the momentum in the system after the collisionm₁ and v₁ represents the mass and the velocity of the physics blockm₂ and v₂ represents the mass and velocity of the ball of puttyv represents the final velocity of the combined mass.the question states the two masses stick together. they combined mass has its own velocity with the body mass the sum of the two objects' massestheir combined momentum is (m₁ + m₂)vto find the magitude of (m₁ + m₂)v, we need to add the vectors on the left-hand side of the equation: m₁v₁ + m₂v₂.note the diagram. i have positioned the vectors in accordance with their directions.the magnitude of the resultant can be calculated using the pythagorean theorem since this is a right triangle situation (north and west are perpendicular)|(m₁ + m₂)v| =  √[ (m₁v₁)² + (m₂v₂)² ]|(m₁ + m₂)v| =  √[ (1.5kg·8.0m/s)² + (0.40kg·20m/s)² ]|(m₁ + m₂)v| =  14.4 kg m/sfor two significant figures (assuming that 20m/s is two), this rounds to 14 kg m/s