An engine converts 5,000 J of thermal energy into 2,500 J of work. What is the efficiency of the engine?
A: 10 percent
B: 20 percent
C: 50 percent
D: 100 percent
A: 10 percent
B: 20 percent
C: 50 percent
D: 100 percent
举一反三
- In an economy, 23 million people are employed and 2 million are unemployed, but 5 million part-time workers would prefer full-time work. What is the unemployment rate? A: 23.2 percent B: 6.7 percent C: 8 percent D: 25 percent
- If the nominal interest rate per year is 10 percent and the inflation rate is 4 percent, what is the real rate of interest? A: 10.0 percent B: 4.1 percent C: 5.8 percent D: 14.0 percent
- What is the percentage of peoplewho have read 2-3 books last year according to the survey result? A: Lessthan 10 percent B: About20 percent C: Morethan 20 percent D: About40 percent
- How much are you expected to give as a tip in the US? A: 15 percent of the bill. B: 50 percent of the bill. C: 20 percent of the bill. D: 12 percent of the bill.
- It is estimated that English borrowings constitute ______of the modern English vocabulary. A: 50 percent B: 50 percent C: 80 percent D: 65 percent