Newton was the first one to suggest that gravity is universal and affects all objects in the universe. Thats why Newtons law of gravity is called the law of universal gravitation. Universal gravitation means that the force that causes an apple to fall from a tree to the ground is the same force that causes the moon to keep moving around Earth. Universal gravitation also means that while Earth exerts a pull on you, you exert a pull on Earth. In fact, there is gravity between you and every mass around youyour desk, your book, your pen. Even tiny molecules of gas are attracted to one another by the force of gravity. Q: Newtons law of universal gravitation had a huge impact on how people thought about the universe. Why do you think it was so important? A: Newtons law was the first scientific law that applied to the entire universe. It explains the motion of objects not only on Earth but in outer space as well.  Newtons law also states that the strength of gravity between any two objects depends on two factors: the masses of the objects and the distance between them. Objects with greater mass have a stronger force of gravity between them. For example, because Earth is so massive, it attracts you and your desk more strongly that you and your desk attract each other. Thats why you and the desk remain in place on the floor rather than moving toward one another. Objects that are closer together have a stronger force of gravity between them. For example, the moon is closer to Earth than it is to the more massive sun, so the force of gravity is greater between the moon and Earth than between the moon and the sun. Thats why the moon circles around Earth rather than the sun. You can see this in the Figure 1.1.
Newton was the first one to suggest that gravity is universal and affects all objects in the universe . That s why Newtons law of gravity is called the law of universal gravitation . Universal gravitation means that the force that causes an apple to fall from a tree to the ground is the same force that causes the moon to keep moving around Earth . Universal gravitation also means that while Earth exerts a pull on you , you exert a pull on Earth . In fact , there is gravity between you and every mass around youyour desk , your book , your pen . Even tiny molecules of gas are attracted to one another by the force of gravity . Q : Newtons law of universal gravitation had a huge impact on how people thought about the universe . Why do you think it was so important ? A : Newtons law was the first scientific law that applied to the entire universe . It explains the motion of objects not only on Earth but in outer space as well . Newtons law also states that the strength of gravity between any two objects depends on two factors : the masses of the objects and the distance between them . Objects with greater mass have a stronger force of gravity between them . For example , because Earth is so massive , it attracts you and your desk more strongly that you and your desk attract each other . That s why you and the desk remain in place on the floor rather than moving toward one another . Objects that are closer together have a stronger force of gravity between them . For example , the moon is closer to Earth than it is to the more massive sun , so the force of gravity is greater between the moon and Earth than between the moon and the sun . That s why the moon circles around Earth rather than the sun . You can see this in the Figure 1.1 .
what does the letter r represent in the equation in question 7?
what does the letter r represent in the equation in question 7 ?
distance
distance