 Now we'll look at a couple of examples using Newton's law of universal gravitation. An astronaut drops their 500 gram glove during an expedition to the moon's surface. Why does the gravitational force acting between the glove and the moon? Firstly, let's draw a force diagram. We know that the astronaut dropped their glove on the surface of the moon and so the glove will be located on the moon's surface. The gravitational force acting on each body will be pointed from its own center of mass toward the center of mass of the other object. So to solve this problem, we need to use Newton's law of universal gravitation where the gravitational force Fg is equal to the universal constant of gravitation multiplied by each of the two masses and divided by the distance between the object's centers of mass. We know that the mass of the glove which is given in the problem is equal to 500 grams or 0.5 kilograms. We know that the mass of the moon, after looking it up, is equal to 7.35 times 10 to the 22 kilograms. We know that the distance between the two centers of mass is about equal to the radius of the moon which is equal to 1,740 kilometers or 1,740 times 10 to the 3 meters. We also know that Big G, the universal constant of gravitation, is equal to 6.67 times 10 to the minus 11 Newton meters squared over kilograms squared. So what is the gravitational force? Let's plug in our numbers and find out. Plugging in our numbers, we can see that the units will nicely cancel to give us Newtons which are the units of force as we would expect. When we plug in the values of our variables, we can observe 0.810 Newtons to three significant figures. So we know between the moon and the glove, there is 810 million Newtons of gravitational force.