When a mosquito hits a car’s window and the car is MOVING, which object (mosquito or car) experiences the larger force?

Answer 1

Neither--they both experience the same force in opposite directions. The two forces form a Newton's 3rd Law pair.

If they experience the same force, then why is the mosquito obliterated while nothing happens to the car? Well for one, the internal structure of the mosquito is not prepared to endure such a force, while the windshield is.

Another way to think about this is in terms of momentum. Suppose the mass of the mosquito is m_q and the mass of the car is m_c, while both are going around the same speed v, but in opposite directions. If we know that the bug will stick to the windshield, then conservation of momentum tells us that m_cv − m_qv = (m_q + m_c)v', where v' is the new velocity of both after the collision. Since the mass of the mosquito is so much less than the mass of the car, m_q + m_c ≈ m_c, and m_cv - m_qv ≈ m_cv. Thus, approximately, m_cv = m_cv', and we see that the speed of the car changes only a negligible amount.