Which type of force requires contact between two objects for one to push or pull the other

What does it mean for a cell membrane to be selectively permable

Which of these serves as a reference for comparison during a scientific investigation? a)outcome variable (dependent variable) b) test variable (independent variable) c)control group d)hypothesis

Which statements describe resources? one of the factors people use when deciding where they will live is the availability of resources. renewable resources have little value for people. resources are unevenly distributed throughout the world. energy is the world resource which has the highest use. the use of nonrenewable resources has decreased in recent history. the use of resources is evenly distributed throughout the world. the world's oil supply will last for the next forty years if its use continues as expected.