1) Consider the four free body diagrams. Free-body diagrams are used to
show the magnitude and direction of all forces acting on an object in a
given situation. Do any of the free body diagrams indicate motion? If
yes, which one(s).

A). No. In all four free body diagrams the forces are
balanced.
B). Yes. In B the book is slowing down because of the
friction force opposing motion.
C). Yes. In the two forces are unbalanced. The upward
force is greater than the force of gravity so the object
moves upward
D). Yes. In B and D. In both cases, forces are unbalanced.
In B. there is a net force to the left; in D there is a net
force upward

    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