effectiveness of monetary policy in classical and keynessian models?

So there is no monetary and fiscal policy in the classical model. The market mechanism will solve all problems if nominal wage and price are flexible. However, to answer your question, I will include the exchange equation into classical model. Because the money supply can cause inflation or even hyperinflation if it cannot be controlled in appropriate way. That means the market will not be able to solve the problems in this case even when wage and price are flexible. More than that, the assumption that the velocity of money is constant, cannot hold.If it increases with inflation, the monetary policy will be less and less effective. The Keynesian model with IS-LM analysis provides the effectiveness of monetary policy with or without fiscal policy. But it has been criticized that wage and price are sticky, so that the monetary policy will not work. At this point, the Keynesian model does not make any sense more than the classical one which assumed flexible wage and price in the first place. Moreover, in the case of stagflation which means that the economy has experienced high inflation and unemployment at the same time, printing money to shift AD to the right will not work.It will increase more inflation instead. In both model, the consumers' confidence has not been taken into account. How about the increase in banks' liquidity, but no bank can loan it out? Just because consumers have no confidence, and stop spending. The confidence might also get lost because of bad government which has no financial discipline. You might know what countries I'm talking about.

0+ and 0-.

Monetarism is deal between government and corporate sector through central bank at the cost of people. Aren't there people who are deprived of being consumers ? US has 500 million.

"I no tax you, I sell you loan cheap ....you fund my party more".

Most of released money is used in playing various markets which calls in inflation....the count swells beyond 5 million.....then some pause, then QE easing ....only God knows why and when.

Fiat money and Fractional banking have made big joke of ISLM model. People still learn and teach that useless stuff. Well, you save 1 $ but banks throw 10 $ in market which gamblers use to play the 5% margin notional markets. Means - without single drop of sweat you get 200 $ in market. Wow!!!

Story repeats for QE - Wow !!! Wow!!!

monetary policy is the process by which the monetary authority of a country controls the supply of money, often targeting a rate of interest for the purpose of promoting economic growth and stability.
For the classical model, it is a model of the economy where it assumed that prices, wages and interest rates are fully flexible so that markets will clear in the long run. Any disequilibrium in prices, wages and interest rates should be quickly resolved. Therefore, this model assumes that output will be determined by real variables such as the amount of capital and not monetary changes.
Keyses was strongly critical of this classical model. He argued that wages, prices and interest rates may not change sufficiently due to rigidities e.g. trade unions.
Keynesian economics is the view that in the short run, especially during recessions, economic output is strongly influenced by aggregate demand (total spending in the economy). In the Keynesian view, aggregated demand does not necessarily equal the productive capacity of the economy; instead, it is influenced by a host of factors and sometimes behaves errantically, affecting production, employment, inflation.
As for classical economics, it assumed flexible prices both in the case of goods and wages. Another main assumption is based on Say's law: supply creates its own demand - that is, aggregate production will generate an income enough to purchase all the output produced.
check out wiki - Monetarism(monetary policy on keynesian theory): keynesians emphasized the use of discretionary fiscal policy and monetary policy, while monetarists argued the primary of monetary policy, and that it should be rules-based.
also check on wiki - classical economics - monetary theory - according to their theories, inflation is caused by banks issuing an excessive supply of money. According to proponents of the theory of endogeneous money, the supply of money automatically adjusts to the demand, and banks can only controls the terms (e.g. rate of interest) on which loans are made.

it's not much, but I hope I've helped ;)

In the classical or long-run view, the economy is assumed to be at full employment. If it is not, it will equilibrate back in a short amount of time due to flexible prices and wages. Therefore, any changes in the money supply will cause a direct change in the price level.

Keynesians believe that the economy can experience downturns, especially ones that are more prolonged and severe than the classicals would assume. Therefore monetary policy can be an effective tool to stimulate the economy through increases in Aggregate Demand.