1._What happens to the electrical energy that is used to start the blender?
2._If the amount of electrical energy delivered to a blender to make it work is 350 watts, what amount is transformed into motion? In heat? In sound?
3._What are the forms of energy not usable?
Answers
Answer:
1. A hand blender runs on electricity. When it is switched on, its blades rotate and a sound is also produced as the motor starts. Thus, electrical energy changes into kinetic energy and sound energy.
2. Energy Conversion Devices and Their Efficiency
A device is a piece of equipment that serves a specific purpose. An energy conversion
device converts one form of energy into another. It is an important element of progress of
society. In fact, one can discuss the history of civilization in terms of landmarks in the
development of energy conversion devices, as illustrated below:
Landmark Event Approximate Date
Emergence of man 4,000,000 B.C.
Emergence of human civilization 5000 B.C.
Development of the water wheel 350 A.D.
Development of the windmill 950 A.D.
Invention of the cannon 1318 A.D.
Development of first atmospheric steam engine (Newcomen) 1712 A.D.
Development of modern steam engine (Watt) 1765 A.D.
Development of high-pressure steam engine (Trevithick) 1802 A.D.
Development of the automobile engine (Daimler) 1884 A.D.
Operation of first nuclear power plant 1954 A.D.
The Industrial Revolution began when James Watt invented the steam engine in 1765;
today we live in the “nuclear age,” marked by the existence of devices (reactors or bombs)
that convert nuclear energy into other energy forms.
An energy conversion device is represented schematically in Figure 4-1. It may be a
very simple gadget, such as an electric toy automobile (which converts electricity into
mechanical energy), or a very complex machine, such as an automobile engine (which
converts the chemical energy of gasoline into mechanical energy).