A system is acted on by its surroundings in such a way that it receives 80 J of heat while simultaneously doing 20 J of work. What is its net change in internal energy?

a. 100 J
b. 60 J
c. zero
d. ?60 J
e. ?100 J


b

Physics & Space Science

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Kinetic Energy: How much energy would be required to accelerate a 77-kg professor from rest to 90% the speed of light? (c = 3.0 × 108 m/s)

A. 1.6 × 1019 J B. 2.1 × 1019 J C. 9.0 × 1019 J D. 2.8 × 1019 J E. 3.5 × 1019 J

Physics & Space Science

Which of the following observations is not a piece of evidence that lends support to aspects of the Big Bang theory?

A) the darkness of the night sky B) the expansion of the universe C) the observed helium abundance in the universe D) the relative motions of galaxies in the Local Group

Physics & Space Science

Which of the following statements about the Michelson-Morley experiment is correct?

A.The physics world was immediately convinced of the null result on ether. B.The interferometer measured large effects from the ether, showing that the velocity of light changes depending on motion with respect to the ether. C.Changing the angle of the interferometer produced different results. D.They found that the interference effects of the ether were not dependent on the direction of motion of the interferometer.

Physics & Space Science

A rock is moving with speed v. If the mass of the rock were tripled and the speed were reduced to v/3, which of the following statements would be true?

a. The kinetic energy of the rock is smaller than in the first case, but the momentum is larger. b. The kinetic energy of the rock is smaller than in the first case, but the momenta of both are the same. c. The kinetic energies of the rocks are the same in both cases. d. The kinetic energy of the rock is 1/9 its previous value.

Physics & Space Science