Radium-226 decays by alpha emission, and the resulting isotope also decays by alpha emission. Write the symbols, including the atomic and mass numbers, for the first and second isotopes produced by these two decays.

Many machines- including inclined planes such as ramps- increase the strength of the force put into the machine but decrease the distance over which the force is applied. true or false

Place me with this question is my last question

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.