What is the potential energy of a 7kg object 4m off the ground ?

please show your work

30 points - when can a theory be modified if a new type of technology allows for new observations that raise new questions? a. immediately, while the questions about the theory are being asked b. after new hypotheses related to the theory are tested in experiments c. only after the new observations disprove all parts of the theory d. while scientists begin to think about how the theory could improve

Abeam of electrons moves at right angles to a magnetic field of 4.5 × 10-2 tesla. if the electrons have a velocity of 6.5 × 106 meters/second, what is the force acting on the electrons? the value of q = -1.6 × 10-19 coulombs.

Which of the following statements are evidence that gases do not always behave ideally? check all that apply.? a. co2 gas becomes dry ice (solid co2) at 1 atm and –78.5 °c. b. when two gases are mixed, they follow dalton\'s law of partial pressures. c. at 4 k and 1 atm, helium is a liquid. d. it is impossible to compress a gas enough so that it takes up no volume.