Three identical boxcars are coupled together and are moving at a constant speed of 28.0 on a level, frictionless track. they collide with another identical boxcar that is initially at rest and couple to it, so that the four cars roll on as a unit. friction is small enough to be neglected. part awhat is the speed of the four cars? part bwhat percentage of the kinetic energy of the boxcars is dissipated in the collision? part cwhat happened to this energy?

Acoil formed by wrapping 80 turns of wire in the shape of a square is positioned in a magnetic field so that the normal to the plane of the coil makes an angle of 28.0° with the direction of the field. when the magnetic field is increased uniformly from 200 µt to 600 µt in 0.400 as, an emf of magnitude 80.0 mv is induced in the coil. what is the total length of the wire?

Which lists the main components of darwin’s theory of evolution? a. random mutations drive evolution; the evolution of a population happens slowly; organisms have common ancestors; organisms do not change. b. natural selection drives evolution; the evolution of a population happens slowly; organisms have common ancestors; organisms change over time. c. natural selection drives evolution; the evolution of a population happens rapidly; organisms have common ancestors; organisms change over time. d. random mutations drive evolution; the evolution of a population happens rapidly; organisms have common ancestors; organisms do not change.

When the force acting on an object points at least partially in the direction of the motion the work done is considered to be negative