There is strong evidence indicating that 3.8 billion years ago there was a higher impact rate. This deduction starts from comparing the number of craters in the lunar highlands with those of the Mary. If this comparison is made, it will be observed that there are 10 times more craters in the highlands than in a similar area of Mary. It should be borne in mind that through radioactive dating processes the samples indicate that there is a slightly greater antiquity in the highlands than those of Maria. This allows us to deduce that if the impact rates had been constant, the highlands would have been 10 times older. They would have to be formed 38 billion years ago, long before the universe itself began.
Therefore one of the most obvious reasons is there are ten times more craters on the older highlands than the Younger Maria.
The "Ideal Mechanical advantage" (IMA) of given pulley is .
Ideal Mechanical advantage of a system is defined by the ratio of achieved or output force to the implied force. In the pulley system above, output force is the resistant force denoted by . The input force is analogous or equivalent to the effort applied i.e. .
Hence by dividing these two forces we calculate the IMA of the above mentioned pulley system which is .
Here's a quick way to find out. Pick up your glasses, bifocals work best, and find the focal length with a flashlight against a book. If I remember right, the object should be magnified and upside down. So, A.