A cyclist and bicycle have a combined mass of 90 kg. Starting from rest, the cyclist rides down a 10 m high hill and up a 7 m high hill without pedaling the bicycle.
What is the potential energy of the cyclist and bicycle at the top of the 7 m hill with respect to the bottom of the 7 m hill?

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?

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is

What is the major limitation to the light microscope?