An iron anchor of density 7800.00 kg/m3 appears 158 n lighter in water than in air. (a) what is the volume of the anchor? (b) how much does it weigh in air?

a) Volume of the anchor is

b) An anchor weighs 1,232.4 N in an air.

Explanation:

Weight of an anchor in water =  W

Weight of an anchor in air = w

w - W = 158 N

Difference in weight will be equal to weight of water displaced as per as Archimedes principle.

Weight of the water =

Volume of an anchor = volume of water displaced = V

Density of water =

Mass of water displaced = m

Volume of the anchor is

Mass of iron anchor = m

Density of the an iron anchor =

Volume of the anchor = V =

Weight of an anchor in an air = w

w = 1,232.4 N

An anchor weighs 1,232.4 N in an air.

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.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.