An energy-saver light-bulb of 11w gives the same illumination as a conventional 60w light-bulb. a typical light-bulb is used on average for five hours a day, how much energy is saved per year by one light-bulb? 2. if each household used eight such light-bulbs, and there are 20 mi- lion households in a country, how much energy would that country save annually?

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Adiver named jacques observes a bubble of air rising from the bottom of a lake (where the absolute pressure is 3.50 atm) to the surface (where the pressure is 1.00 atm). the temperature at the bottom is 4.00 ∘c, and the temperature at the surface is 23.0 ∘c.what is the ratio of the volume of the bubble as it reaches the surface (vs) to its volume at the bottom (vb)? if jaques were to hold his breath the air in his lungs would be kept at a constant temperature. would it be safe for jacques to hold his breath while ascending from the bottom of the lake to the surface?

Which of the following are forms of phase changes a. freezing b. condensation c. heating d. exchanging