Question

pulleys and mechanical advantage
read the passage and answer the following question(s).
pulleys and mechanical advantage
a pulley is a type of machine that changes the direction of the input force. the input force is the force applied to the pulley, and the output force is the force of resistance applied by the load.
the input force of a pulley system is determined by dividing the output force of the load by the number of ropes supporting the load. the work done to move the load is calculated by multiplying the applied force by the distance the object moved in the same direction as the applied force. the equations to calculate the work done are shown.
work done to the pulley = finput x distance and work done by the machine = foutput x distance
where finput is the input force and foutput is the output force
the diagram shows four pulley systems supporting the same mass. each pulley has a different number of ropes supporting the mass.
question 9.
a helium atom before and after it undergoes a change is shown.
which statement best describes the atom after the change has occurred?
a. the atom is a positively - charged ion.
b. the atom is a negatively - charged ion.
c. the atom is a positively - charged isotope.
d. the atom is a negatively - charged isotope.
question 10.
use the drop - down menus to compare atoms, ions, and isotopes.
atoms vary based on their number of (select), ions vary based on their number

Explanation:

For Question 9: A helium atom has 2 protons, 2 neutrons and 2 electrons initially. After the change, one electron is lost. Since protons are positively - charged and electrons are negatively - charged, losing an electron results in a positively - charged ion.
For Question 10: Atoms vary based on their number of protons (which determines the element). Ions vary based on their number of electrons (a gain or loss of electrons creates an ion).

Answer:

Question 9: A. The atom is a positively - charged ion.
Question 10: Atoms vary based on their number of Protons; Ions vary based on their number of Electrons.