Travelers on the california and santa fe trails had to cross deadly?

According to the video, two of the ways government can play a role in the economy is by protecting property rights and to

Mr. mann's science students were experimenting with speed. they set up a 1 meter (100 cm) track. the students used balls instead of cars. the balls were different sizes and made of different materials. four at a time, students rolled balls around the track to see which had the fastest and slowest speeds. some of their data are shown in the table. which ball will take the longest to complete one lap around the track?

The principal effector function of igm is