Plunging oil prices have pummeled profits at energy companies and a surging dollar has hit companies that depend heavily on overseas sales. Earnings season got underway this week and average earnings per-share for corporations in the Standard & Poor's 500 index are projected to drop by 3.2 percent in the first quarter compared with the same period a year ago, according to S&P Capital IQ estimates. The big drop is hitting energy companies hard and their earnings are forecast to have dropped by almost two thirds in the first quarter. Many economists predict that falling oil prices will eventually benefit the economy as a whole, because lower gas prices will give consumers more money to spend. [...] while the steep drop in oil prices is having an immediate impact on the bottom line of energy companies, its beneficial impact on other parts of the economy is more nuanced. Among other things, health care companies are benefiting from the introduction of the Affordable Care Act, and financial companies are continuing their drawn-out recovery after the financial crisis.