4. A 2000 kg SUV traveling at 7 m/s south runs into the rear end of an 800 kg compact car sitting at a stop light in an elastic collision. If the compact car is
going forward at 7 m/s right after the collision, how fast is the SUV traveling?
5. Beaker and Honeydew are driving bumper cars. They spot each other across the
rink and head straight for each other at full speed. Honeydew and his car (130 kg
I
total) head east at 3.5 m/s while Beaker and his car (110 kg total) head west at
3.0 m/s. They have an elastic collision when they meet and Honeydew (and car)
bounces backwards at 2.4 m/s. What is Beaker's speed after the collision?

    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

Ithink the answer is fusion