Place the four steps in order to explain how an electric motor works. 1.A loop of wire is placed between the poles of a permanent magnet. The wire is attached to a commutator. Current runs through the electromagnet. 2.The direction of the current switches, causing the poles to switch and causing the magnetic field to reverse. 3.Electromagnetic forces, caused by the interaction of the electromagnet and permanent magnet, cause the electromagnet to rotate. 4.The electromagnet continues to rotate, causing the direction of the current to continue to change while the wire turns.

it is the most commonly accepted one

gas

explanation:

smoke is the matter of a gas

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied