According to McLuhan, why is the telephone a "cool" medium and the radio "hot"?

A distinction made by McLuhan between media such as print, photographs, radio, and movies (hot media) and media such as speech, cartoons, the telephone, and television (cool media). Hot media are ‘high definition’ because they are rich in sensory data. Cool media are ‘low definition’ because they provide less sensory data and consequently demand more participation or ‘completion’ by the audience (a useful mnemonic is to imagine that hot media are too hot to touch). Note that McLuhan was not referring to the issue of the relative cognitive effort involved in the use of different media. Arguably, in McLuhan's terms, television has grown hotter since the 1960s as its technical picture quality has improved, so these terms are relative. Critics of McLuhan's concept have argued that it reifies the medium, underestimating differences within the same medium; the degree of audience engagement does not depend primarily on the medium itself (although its affordances may play a part), but on its content and the ways in which the medium is used on specific occasions within specific contexts. See also McLuhanism; compare high and low involvement.

Explanation:

native american contribution: the patriots from britain learn how to hunt, fish, and introduce diversity within cultures.

african americans: indirectly introduced the idea of diversity to americans. africans coming to america because of slavery taught white americans that people come from different backgrounds and colors. it also built america's economic stability for a great period of time. 

women: make america what it is today. there are some societies that are in the world currently that do not give women the same right we give women here in the united states. because women have rights here in the united states, other countries' citizens strive to come to america, especially women, since they have equal rights in the united states. this is important because america is seen and desired by many in the world. 

children: children are our future. we learn from our elders and carry out things the same or differently learning from america's history. we continue tradition and change tradition if it is needed.