A train is accelerating at a rate of 2.0 km/h/s. Its initial velocity is 20 km/h. What is its velocity after 30 seconds? PLEASE HELP

What is a possible result of higher air temperature caused by global warming

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.

What is friction? how does it affect the motion of an object?