Which timeline best shows the history of the development of cell theory? 1685 Virchow 1838 Schleiden 1855 Hooke 1600 1700 1800 1900 1878 Schwann 1832 Leeuwenhoek 1885 Hooke 1838 Schleiden 1855 Virchow 1600 1700 1800 1900 1878 Leeuwenhoek 1839 Schwann 1865 Hooke 1838 Leeuwenhoek 1855 Virchow 1600 1700 1900 1676 Schleiden 1839 Schwann 1685 Virchow 1838 Schwann 1855 Hooke 1600 1700 1800 1900 1678 Leeuwenhoek 1839 Schleiden

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?