AnswersDISD CR Physics 2020-2021Universal Law of Gravitation

Universal Law of Gravitation — Unit test Answers

3 verified answers
1
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Cecelia dropped a ball from a height of 2 m. The ball fell in a straight path down to the ground.

A
tossing it horizontally at a slower speed
B
tossing it horizontally at a faster speed
C
dropping it from a shorter distance
D
dropping it from a greater distance
2
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Which best describes the present-day universe?

A
opaque, expanding very slowly, stars produce heavy elements
B
transparent, expanding at an accelerated rate, stars produce heavy elements
C
opaque, expanding at an accelerated rate, stars produce only hydrogen and helium
D
transparent, expanding very slowly, stars produce only hydrogen and helium
3

Simon is writing a story about an astronaut whose spacecraft has been boarded by space pirates. The astronaut has her lucky penny in her hand behind her back as the space pirates break into the control room. She has just locked the controls so that the ship is accelerating in the direction of the control room’s ceiling. Simon wants the astronaut to use the penny to hit a button on the control panel to turn off the lights and escape. The button is located a short distance behind and below the astronaut’s hands.

A
The astronaut should toss the penny straight up as it will appear to fall in an arc because objects in an accelerating frame of reference behave in the same way as they would in a gravity field.
B
The astronaut should just let the penny go, as the control panel will accelerate upward and curve toward the astronaut because there is no gravity field.
C
The astronaut should toss the penny horizontally straight behind her as it will appear to fall in an arc because objects in an accelerating frame of reference behave in the same way as they would in a gravity field.
D
The astronaut should toss the penny in a straight line toward the button because the penny will follow a straight line in space rather than appear to move in an arc as it would in a gravity field.
4

Which concept was supported by taking measurements of the same stars at night and then again during solar eclipses?

A
gravitational lensing
B
principle of equivalence
C
gravitational time dilation
D
gravitational redshift
5

A Hertzsprung-Russel diagram is shown.

Question illustration
A
red giants
B
white dwarfs
C
supergiants
D
main sequence
6

Leo drew a force diagram to represent a satellite in orbit around Earth.

Question illustration
A
make the Fg vector longer
B
change the vector labeled Fair so it is labeled Fp
C
add an Fp vector at the center and pointing left
D
remove the Fair vector
7

The emission spectrums are known for the elements below.What elements are in the unknown sample? Select 2 options.

Question illustration
A
boron
B
lithium
C
hydrogen
D
helium
E
potassium
8

What is the study of the spectra produced from the emission and absorption of electromagnetic radiation?

A
study of absorption spectrums
B
study of emission spectrum
C
nanotechnology
D
spectroscopy
9

What is luminosity?

A
the amount of energy a star emits in a unit of time
B
the brightness of a star as seen from Earth
C
the average temperature of a star during its life cycle
D
the degree of shift toward the red end of the spectrum
10

What are some applications of the field of spectroscopy? Select 5 options.

A
for identifying elements in a sample
B
for determining the distance and velocity of galaxies
C
for producing neon lights
D
for determining types of chemical bonds
E
for use in medical imaging devices
F
for killing bacteria in foods
11

In the equation for the gravitational force between two objects, what does G represent?

A
the gravitational constant
B
the gravitational force
C
the gravitational field strength
D
the gravitational acceleration
13

Clara made a chart to summarize some of the evidence that supports the big bang theory.Which best describes Clara’s error?

Question illustration
A
During redshift, the light source and observer move closer together, not farther apart.
B
The CMB is blue-shifted, not red-shifted, to the microwave region.
C
The temperature of the CMB is cooler, not hotter, than at the time of the big bang.
D
The redshift indicates approaching, not receding, galaxies.
14

Which formula can be used to find the centripetal acceleration of an orbiting object?

A
ac =
Option A
B
ac =
Option B
C
ac =
Option C
D
ac =
Option D
15

Chris is studying the theories of Newton and Einstein.Which theory explains why gravity between two objects changes when the distance between them changes?

A
Einstein’s theory because he suggested that the more distance there is between objects, the more space-time curves and the greater the strength of gravity is
B
Einstein’s theory because he suggested that the more distance there is between objects, the more space-time curves and the weaker the strength of gravity is
C
Newton’s theory because he suggested that the greater the distance between objects, the greater the pull of gravity
D
Newton’s theory because he suggested that the greater the distance between objects, the weaker the pull of gravity

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