In what era did the first land plants appear?

The cyclist has a mass of 50 kg and is accelerating at 0.9 m/s^2. what is the size of the unbalanced force F acting on the cyclist?

A 70-kg person walks at a steady pace of 4.4 km/h on a treadmill at a 5.0% grade (that is, the vertical distance covered is 5.0% of the horizontal distance covered).

Rubber rods charged by rubbing with cat fur repel each other. Glass rods charged by rubbing with silk repel each other. A rubber rod and a glass rod charged respectively as above attract each other. A possible explanation is that a.

Which of these is a source for particulate matter in the air? a. automobiles b. dust c. fires d. all of the above

how can you use the periodic table to determine the average number of neutrons in element has even though the number of neutrons is not listed

A glass window is a clear object that light passes through as it travels in a straight line. This is a good example of A. refraction of light. B. transmission of light. C. absorption of light. D. reflection of light.

Why is net force a vector sum A. All forces have direction and magnitude B. Forces can only be attractive C. All forces are contact forces D. There are four fundamental forces

Does the elf owl's small size allow it to live in cacti

If grapefruit juice has a ph of 3.0 and egg white have a ph of 8.0, which contains more h + ions? how many more?

Consider a single photon with a wavelength of λ, a frequency of ν, and an energy of e. What is the wavelength,? Consider a single photon with a wavelength of λ, a frequency of ν, and an energy of e.