An ice pack and a room temperature cola can are sealed inside an insulated container. Energy can transfer among the can, the ice pack and the inside of the container, but cannot leave the container. What type of system is this?

Two particles of masses m and 2m are placed on a smooth horizontal table. a string, which joins these two masses, hangs over the edge supporting a pulley, which suspends a particle of mass 3m.the pulley has negligible mass. the two parts of the string on the table are parallel and perpendicular to the edge of the table. the hanging parts of the string are vertical. find the acceleration of the particle of mass 3m.

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

(**i would really appreciate if this was answered soon** ) which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?