a man is using an axe to chop down a tree. After a short time after the axe hits with tree the man hears a clear echo he estimates that the echo is 3 seconds after the axe hits the tree. suggest what type of obstacle might have caused such a clear echo​

What is the measure of how much matter is in an object and that can be measured using a balance? a. height b. volume c. weight d. mass

Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. which one, if either is correct? a. beryl, because low thermal conductivity results in low heat transfer. b. beryl, because low thermal conductivity results in high heat transfer. d. sapphire, because low thermal conductivity results in high heat transfer. e. neither, because low heat transfer is desirable both in summer and in winter.

Why should the wavelength scale of spectroscope be calibrated