The actual mechanical advantage of a machine
a. cannot be less than 1
b. decreases as the input distance increases
c. increases with greater friction
d. is less than the ideal mechanical advantage of the machine

Scientists follow specific processes in order to determine valid explanations and conclusions from observations. david observed strange lights in the sky above his home outside of roswell, new mexico. the only explanation that makes sense to him is that there are ufos in the area. what should david do next to verify his explanation?