A2kg mass is moving on a frictionless airtrack. it collides into a motionless 1.5 kg mass.
what is the combined speed of the two masses if they stick together on impact

Explanation:

From the law of conservation of momentum, the sum of initial momentum equals the sum of final momentum

Momentum, p=mv where m is the mass and v is the velocity

where is the common velocity, and are velocities of 2 Kg moving mass and motionless 1.5 kg mass respectively, and are masses of 2 Kg moving mass and motionless 1.5 kg mass .

Since the 1.5 Kg mass is motionless, it's velocity is zero hence

By substitution

The answer is C.

Explanation:

Every point mass attracts every single other point mass by a force acting along the line intersecting both points. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between them. In magnitude, the force they apply each other is the same. Therefore, the force that the windshield exerts on the bug and the force that the bug exerts on the windshield are the same magnitude.