To compare the hearing capacities of 5 of his friends, Ravi designs a simple experiment. He places a CD player at the end of a long hall containing a CD with 5 well-known songs. One by one each person hears the same 5 songs he plays softly but at a pre-determined volume.

Each person starts at a distance of 1 metre from the player and moves away from it. The distance at which a person says that he cannot hear the song any more, is noted. Others are not in the room when 1 person is hearing the songs.
Which of these steps may increase the reliability of the results obtained?

A)having each person listen to just 1 song instead of 5
B)allowing all people to stay in the room for the entire experiment
C)having each person start from far and walk towards the C
D )player Dvarying the volume for the different songs being played

An automobile of mass 2000 kg moving at 30 m/s is braked suddenly with a constant braking force of 10000 n. how far does the car travel before stopping?

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?

What is the acceleration of a spaceship that is initially at rest and then speeds up to 220 m/s in 20 seconds