Why dose a phonograph - record attract dust partiules just
. after it is cleaned?

Why does a phonograph record attract dust particles just after it is cleaned?

In the "before" part of Fig., car A (mass 1100 kg) is stopped at a traffic light when it is rear-ended by car B (mass 1400 kg). Both cars then slide with locked wheels until the frictional force from the slick road (with a low mu_k of 0.10) stops them, at distances d_A = 8.2 m and d_B = 6.1 m. What are the speeds of (a) car A and (b) car B at the start of the sliding, just after the collision? (c) Assuming that linear momentum is conserved during the collision, find the speed of car B just before the collision. (d) Explain why this assumption may be invalid.