Why does ice float when it is placed in
a liquid water?
a. because the density of ice is greater than water
b. because the density of ice and water are the same
c. because the ice has a greater weight than water
d. because the density of ice is less than water

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.