Question

Question 1: Explain why a pound of TNT contains less energy than a pound of chocolate chip cookies but is more dangerous.  

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Question 2: Find the typical energy consumption of a man in a day and determine his daily average power in watts.

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Question 3: A person can do a sustained work with the power of about 100 W and at the same time produce 3 times amount of the heat. How many bananas should the person eat if he/she wants to make up for the energy lost in a half-hour work?  

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Question 4: Express the kinetic energy of a 140-pound person running at the speed of 6 mph (miles per hour) in terms of joules.  

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Answer 1

1. As you hint in your question ,it's all about how quickly the energy comes out .TNT will release all that energy in millisecond whilst a chocolate cookies takes a minute .

Technically TNT is high explosive the explosive wave (the wave of ignition ) propogates faster than the speed of sound compare it to gunpowder. For example which is a low explosive ,explosive wave is slower then the speed of sound . Your cookie won't explode because burning front propogates too slowly . You need to speed that up try dunking the cookie in liquid oxygen for few minute .

2. Energy consumption of a man in a day

E=p*t/1000

Where E=energy in kwh

P= power in watt

t is hours

Energy conupumtion of man in day

E= P* 60*60/1000

E= 3600*P/1000

E= 36 P

A man in a rest produce power 100 watt over period in few minute. Produce 300-400 watt

Avaarge power daily 75 watt.

4. Kinetic energy KE= 1/2 m v^2

= 1/2 * 140* 36*0.45* 0.44* 0.44

= 21420*0.45* 0.44*0.44

= 210.83 Joule

KE= 210.83 joule