31. Which materials would most likely be used by designers of ornithopters to mimic the bone structures of pterosaur wings? A. heavy metals to prevent bends and tears in the wings B. wooden replicas of bones to create identical structures for the devices C. lightweight metals and open-space structures for the wings D. plastic replicas of bones that have a completely filled-in structure

There is a theory that indicates that dinosaurs became extinct when about 65 million years ago, a large asteroid hit the earth surface. dust caused by this collision blocked the sunlight reaching the earth's surface and many forms of life became extinct due to the cold. fearing this threat, how large the radius of an asteroid should you be looking for if the dangerous asteroid size is approximately the same as the one that killed the dinosaurs? available data suggests that about 18% of that asteroid's mass ended up as a dust spread evenly over earth after eventually settling out of the upper atmosphere. about 0.0180 g/cm^2 of dust, which is chemically different than the earth's rock, covered the earth's surface. typical asteroids have a density of about 1.9 g/cm^3. now that we know the size of the asteroid, how much energy was released during impact, assuming all of it was just the kinetic energy of the asteroid right before the impact?

The diagram shows a series of volcanic island and a hot spot determine the direction of movement of the tectonic plate that for the island

A20 cm long spring is attached to a wall. the spring stretches to a length of 22 cm when you pull on it with a force of 100 n. what is the spring constant