a train moves east with a speed of 45m/s. a man on the train walks west with a speed of 0.4m/s relative to the train. how long does it take the man to move 10m relative to the train ?

How to tell if a molecule is polar or nonpolar with electronegativity

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.

Positive ions differ from neutral atoms in that