Which statement correctly compares speed to velocity? a. speed is how fast an object is moving over distance/time. velocity is only the direction that the object travels. b. speed is how fast an object is moving over distance/time. velocity is the rate at which an object changes position, , over displacement/time c. velocity and speed mean the same thing d. velocity is how fast an object is moving over distance/time. speed is the rate at which an object changes position, over displacement/time

B. Speed is how fast an object is moving: speed = distance/time.

Velocity is the rate at which an object changes position: velocity = displacement/time

Explanation:

Distance is a scalar quantity. It has only magnitude. So, distance/time is also scalar. If you are travelling at 100 km/h, that is your speed, because you could be going in any direction.

Displacement is a vector quantity. It has both magnitude and direction So, displacement/time is also a vector. If you are travelling east at 100 km/h, that is your velocity, because you are stating both your speed and the direction

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.