Injections such as investment, government spending, or exports increase the total expenditure in the economy. This rise in aggregate demand shifts the AD curve to the right. If the economy is near full employment, this excess demand pulls prices upward, resulting in demand-pull inflation.

The circular flow diagram is a fundamental economic model that depicts how money, goods, and services move between households and firms. It demonstrates the interdependence of different sectors, showing how income received by households for factors of production is spent on goods and services produced by firms.

The velocity of money is defined as the ratio of nominal GDP to the money supply. Because different definitions of money (M1, M2, etc.) exist, the calculated velocity varies depending on the chosen monetary aggregate. Consequently, determining whether velocity is truly stable or merely an artifact of measurement techniques remains a significant challenge in empirical monetary economics.

According to the quantity theory of money, an increase in the money supply, if not matched by a corresponding increase in the output of goods and services, typically leads to an increase in the general price level. This phenomenon is known as inflation. While short-term effects on growth or unemployment may occur, the most direct and widely recognized long-term consequence of excessive monetary expansion is inflationary pressure on the economy.

Milton Friedman, a leading figure of the Monetarist school, argued that the money supply should grow at a predictable rate to maintain price stability. While the question attributes the adaptation to aggregate demand to him, it is important to note that Friedman generally favored a fixed rule for money growth rather than discretionary adjustments. This explanation acknowledges the source's attribution while clarifying his broader monetarist stance.

The velocity of money refers to the frequency at which a single unit of currency is used to purchase newly produced goods and services within an economy over a specific period, typically measured annually. It is a key component of the Quantity Theory of Money, representing the speed at which money circulates through the economy.

The simple Quantity Theory of Money (MV=PY) assumes velocity (V) is constant. If the demand for money depends on the interest rate, then velocity becomes a function of the interest rate rather than a constant. Consequently, changes in the money supply do not have a predictable, proportional effect on nominal income, meaning the strict version of the quantity theory of money does not hold.

Monetarism is an economic school of thought that posits that the money supply is the primary determinant of nominal GDP and short-term economic fluctuations. Monetarists argue that central banks should focus on maintaining a steady growth rate of the money supply to ensure price stability and sustainable economic growth, rather than attempting to fine-tune the economy through discretionary fiscal policy.

The quantity theory of money, expressed as MV=PY, posits that in the long run, changes in the nominal money supply (M) lead to proportional changes in the price level (P), assuming velocity (V) and real output (Y) remain constant. This reflects the classical dichotomy where money is neutral in the long run, affecting nominal variables but not real variables like output or employment.

According to the quantity theory of money, an increase in the money supply leads to an increase in the price level in the long run. While the initial impact is often a reduction in interest rates, the question specifically identifies the price level increase as the outcome. This reflects the relationship where more money chasing the same quantity of goods leads to inflationary pressure on prices.