Which best explains how the human body obtains energy from food?
a. by inhaling oxygen into the lungs
b. by removing dangerous wastes
c. by exhaling carbon dioxide
d. by breaking chemical bonds?

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?

Awave has a wavelength of 15 mm and a frequency of 6 hertz. what is its speed?

If a grape were placed in a hypertonic solution what would happen and why?