Tutor profile: Andrew Z.
Subject: US History
What was the purpose of the Marshall Plan? Why would the United States give away so much money to rebuild Europe after World War II?
In 1948, the Marshall Plan was intended to build a sense of good will in Europe. While it seemingly did not have any strings attached, countries who received Marshall Plan aid were more or less expected to shift towards a democratic government. By supplying European nations, particularly those in Eastern Europe, with "free money" to rebuild after the war, the United States hoped to build a sense of good will while spreading democracy across Europe. By doing so, not only would these countries become democratic and pro-US, but they would prevent communism from spreading outwards from the Soviet Union. First brought up in George Kennan's "Long Telegram" the year before, containment's goal was to keep communism limited to the Soviet Union before it became a major threat to the United States and the democratic system of rule.
Subject: European History
What was the primary cause of WWI?
The main cause of World War I was a series of secret alliances that drew one nation after the other into a commitment to fight on behalf of its allies. In 1914, a Serbian nationalist named Gavrilo Princip of the Serbian nationalist group, The Black Hand, assassinated Archduke Franz Ferdinand of Austria. In retaliation, the Austro-Hungarian Empire declared war on Serbia. Russia had a secret alliance to protect Serbia and so they began to prepare for war against Austria-Hungary. On the other side, Germany had secretly promised the Austro-Hungarian Empire that they would side with them, so they began with war preparations of their own. The French were secretly aligned with the Russians and so they declared war against Austria-Hungary and Germany. Suddenly the assassination of Franz Ferdinand had pitted the world powers of Austria-Hungary and Germany against the Russians and the French. The United Kingdom would join soon after and the United States would join by 1917. Had the Auto-Hungarian Empire known the full extent of these secret alliances, they may have never declared war on Serbia and WWI may never have happened.
If I am standing still, why is the net force acting on me 0 N? I understand that I am not moving but isn't the force of gravity pulling down on me?
It is important to remember that force is equal to mass times acceleration (F=ma) and net force is the sum of all forces. You are correct in assuming that gravity is pulling down on you with a force equal to the acceleration due to gravity times your mass (F=9.81 * mass). However, there is a second force at play in this scenario. When you are standing, the ground actually "pushes back" against you! This is known as the ground reaction force (GRF). Since you are not moving, the net force must be equal to zero (remember net force is the sum of all forces) and therefore the GRF must be equal and in the opposite direction of your weight so that they cancel out. Therefore the GRF is equal and opposite to the direction of gravity acting on your body and the net force ends up equaling 0 N.
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