According to general relativity, why does earth orbit the sun? a. earth and the sun are continually exchanging photons of light in a way that holds earth in orbit. b. earth interacts with the magnetic field of the sun. c. matter contains quarks, and earth and sun attract each other with the "color force" between their quarks. d. the mass tied to the sun warps the space around it, in a similar fashion to a large mass at the center of the trampoline.

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

What property is a characteristic of a substance that can be observed and does not change the identity of the substance

Asystem containing an ideal gas at a constant pressure of 1.22×10^5 pa gains 2140 j of heat. during the process, the internal energy of the system increases by 2320 j. what is the change in volume of the gas?