Frederick has a lawnmower that is fueled by gasoline. His science teacher told him that not all of the energy stored in the gasoline in the lawnmower is converted into the energy of motion that spins the lawnmower blade. Which of the following statements is the most accurate explanation of this situation?
A.
An isolated system always loses energy to its environment.
B.
The law of conservation of energy is not obeyed by isolated systems.
C.
Energy can leave an open system and enter the surroundings.
D.
The total amount of energy never changes in an open system.

How does the space charge width change with forward and reverse bias? also, calculate the space charge width for a reverse bias of 4v on a silicon pn junction at t = 300k and doping concentrations of na = 5x1015cm-3 , nd = 5x 1016 cm-3 .

Ogle–2013–blg–0723 is an exoplanet that is similar to earth in size and proximity to its star. this exoplanet has mass m=4.18×1024kg and radius r=5.66×106m. an astronaut whose weight on earth is w=735n lands on the planet. a. calculate m, the mass of the astronaut. b. calculate gp? , the acceleration due to gravity on the surface of ogle–2013–blg–0723. c. calculate wp? , the weight of the astronaut on the surface of ogle–2013–blg–0723. d. calculate v, the minimum velocity required to put an object into orbit above ogle–2013–blg–0723. e. calculate t, the time required to complete an orbit around ogle–2013–blg–0723.

According to social exchange theory, altruistic behaviors benefit the individual who performs them. t/f