Why does a hot air balloon float?
1. the shape of the balloon provides lift.
2. the volume of the air displace by the balloon is less than the volume of the balloon.
3. the weight of the air displaced is less than the volume of the balloon.
4. the weight of the balloon is less than the weight of the air displaced by the balloon.

Which identifies the main purpose of biological taxonomy?

Sally and sue were investigating the topic of friction in science. they used a small car and a ramp as seen in the picture to test what they were learning. they knew that they slipped easily on waxed floors but not on carpet, so they decided to change the material on the surface of the ramp to see what happened. they planned to use glass, carpet, aluminum foil, and sandpaper and run the car down the ramp over each surface. what would be the best research question to guide the girls' experiment? a) does the amount of surface area affect the friction on the moving car? b) will the car travel fastest on the glass surface? c) how does the angle of the ramp affect the speed of the car? d)do rougher surfaces tend to create more friction than smooth surfaces?

Recombinant dna is the merging of dna from unrelated organisms to create new genetic varieties is assembled in the lab from mononucleotides was part of the green revolution of the 1960s is pollination of one plant by another of the same species is cross-pollination of one plant by a different species