Question

check your understanding (p. 149) #1-4

1. name two factors that reduce the efficiency of machines.
2. list three benefits of becoming more energy efficient.

Explanation:

Question 1

To determine factors reducing machine efficiency, we consider physical principles. Friction occurs when surfaces rub, converting mechanical energy to heat, wasting energy. Air resistance (for moving machines like vehicles) opposes motion, requiring extra energy to overcome, thus reducing efficiency.

Energy efficiency benefits are analyzed from economic, environmental, and resource perspectives. Cost savings: less energy use means lower utility bills. Environmental protection: reduced energy consumption cuts greenhouse gas emissions (from fossil fuel - based energy production). Resource conservation: less energy demand preserves finite resources like coal, oil, and natural gas for future use.

Answer:

1. Friction (between machine parts, converting useful energy to heat).
2. Air resistance (for machines in motion, opposing movement and wasting energy).

Question 2