Select all that apply. thermal conductivity is dependent on the area of exposure temperature difference between the objects thickness of the material color of the material

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth

When an object is heated it contracts. a. true b. false

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.