(Comparing the answers for this question and the last one, notification that the gravitational force that the Sun exerts on the Moon is around 100 times as a lot as the gravitational force that the Planet exerts on the Moon. Why, then, does the Moon orlittle bit the Earth and also not the Sun? ) Ch 12 Think & Exordinary Answers: No, this label is not cause for alarm! The same point can be said around every object in the universe - including you! The exact same amount of force. The forces "Planet pulls Moon" and also "Moon pulls Earth" are a Newton"s third Law action/reaction pair. 500 N towards the center of the Earth. This gravitational force is the force we frequently contact her weight. If the gravitational pressure of the Sun on the planets suddenly disshowed up, they would certainly move off through the velocity that they had at that immediate (Newton"s first Law). So, they would certainly move in a directly line tangent to their orlittle bit, at constant rate. (a) Yes, if the Moon were twice as substantial, the gravitational force of the Earth on the Moon would certainly be twice as a lot, because the gravitational force is proportional to both masses involved. (b) Yes, the gravitational pressure that the Moon exerts on the Earth would certainly double likewise (according to Newton"s Third Law). A rocket going from the Planet to the Moon would call for more fuel. Due to the fact that the Planet has more mass than the Moon, the Earth will exert a bigger gravitational pressure on the rocket than the Moon would (points weigh much less on the Moon). This means that the rocket would certainly need to exert a bigger force to balance its weight leaving the Earth than leaving the Moon. Since the rocket exerts a larger force leaving the Earth, it must do more occupational to leave the Earth, which takes even more energy (in the create of chemical potential energy stored in the rocket fuel). Gravitational forces on a galaxy close to the "edge" of the Universe. (Not all pressures are displayed.) Net pressure on a galaxy near the "edge" of the Universe. The monitoring that the expansion of the Universe is slowing dvery own is constant through the law of gravity. Eincredibly object in the Universe attracts every various other object in the Universe with a gravitational force. The diagram on the left above mirrors some of the gravitational pressures on a galaxy close to the "edge" of the universe. Looking at the diagram you have the right to see that all of the pressures on this galaxy allude "inward", because all gravitational forces are attractive. This indicates that the net force on this galaxy points "inward" toward the "center" of the Universe, as shown in the diagram at appropriate over. So, if the galaxy is relocating ameans from the "center" of the Universe (an widening universe), then the net force on the galaxy will act to sluggish the galaxy down, and the growth of the Universe have to be slowing dvery own. However before, current monitorings (because the publication of your text) seem to indicate that the development of the Universe is in reality NOT slowing dvery own - in fact, the Universe appears to be speeding up. This is contrary to the behavior that the law of gravity predicts as described above. This is a room of extremely heated and intense research and discussion at the minute. If the Universe"s expansion is really accelerating, then there hregarding be some previously-undetected force that is driving it. What can that force be?

## Ch 12 Think & Solve Answers

If the Earth"s diameter doubled and also its mass additionally doubled, your weight would be fifty percent as much as now. Your weight is the gravitational force in between you and also the Earth. Doubling the mass of the Earth would certainly double your weight, because gravitational pressure is straight proportional to mass, yet doubling the radius (which doubles if the diameter doubles) would decrease your weight by a element of 1/4, given that gravitational force is inversely proportional to the square of the radius.

You are watching: Why did newton think that a force must act on the moon

See more: Which Definition Of Insight Best Matches The Definition Given In This Dictionary Entry?

Mathematically:
If you were twice as much from the facility of the Earth as you are now, your weight would certainly be 1/4 of its present worth (See #32).