Work done within an isolated system can increase the energy of the system.
Indicate whether the statement is true or false
[Ques. 2] About how old was the universe when the microwave background radiation that Penzias and Wilson discovered first became visible?
a. 1 microsecond (10-6 second) when the electromagnetic force separated out from the electroweak force.
b. 3 minutes, the start of the period that ended with typical photons unable to produce electron-positron pairs.
c. 300 thousand years, when matter in the universe became transparent to photons.
d. 1 million years, when the strong force separated out.
e. 30 million years, when the strong force separated out.
[Ques. 3] Momentum is conserved only when there is no friction.
Indicate whether the statement is true or false
[Ques. 4] The sequence of steps in which the four forces separated out from a single force after the Big Bang was:
a. first the gravitational force separated from electroweak combined with strong; then electroweak and strong separated; then electroweak separated into weak and electromagnetic.
b. first the electroweak force separated out; then gravitation separated out from strong; then electroweak separates into electromagnetic and weak.
c. first the strong force separates; then electroweak separates out from gravitational; then electroweak separated into electromagnetic and weak.
d. first electroweak force separated; then electroweak separated into electromagnetic and weak; then strong and gravitational separated.
e. first gravitational force, electroweak, and strong forces separated into three; then electroweak separated into electromagnetic and weak.
[Ques. 5] Linear momentum is conserved in all collisions.
Indicate whether the statement is true or false
[Ques. 6] During the inflation that started at about 10-37 seconds after the Big Bang, the universe expanded by:
a. up to 1050 in as little as 10-47 seconds.
b. up to 1042 in as little as 10-40 seconds.
c. up to 1030 in as little as 10-36 seconds.
d. by about a factor of 10 up to the present time.
e. by no significant amount.
[Ques. 7] Kinetic energy is conserved in elastic collisions.
Indicate whether the statement is true or false
[Ques. 8] How long ago did the Big Bang occur?
a. About 6,000 years ago.
b. 15 thousand years ago.
c. 15 million years ago.
d. 15 billion years ago.
e. 15 trillion years ago.
[Ques. 9] The momentum of an object never changes.
Indicate whether the statement is true or false
[Ques. 10] In superstring theory the fundamental objects from which all forces and matter are built are:
a. Planck lengths.
b. gravitons.
c. gluons whose size of about 10-25 m is the smallest distances in nature.
d. loops of material that cannot be further subdivided, whose size of about 10-35 m is the smallest distance in nature.
e. quarks whose size of about 10-25 m is the smallest distance in nature.
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