Can someone answer this science question ?

Volcanoes: Most volcanoes are formed by the movement of tectonic plates on the surface of the earth. These plates basically float on mantle. Sometimes these plates will sink into the mantle. The rock becomes so hot it melts. Gradually, the molten rock (the melted rock) will then make it's way back up. When it surfaces it, we call it "lava". As lava layers, it slowly forms a volcano. 

Valleys: Basically formed by a river valley. The stream shapes the Earth's crust over time into a funnel-like v-shape or u-shape (depending on the flow of the stream).

Mountains: When plates collide and through pressure start building up into a cone shape.

    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