Work of a Blowgun: Amazon forrest hunters shoot poisoned darts through hand-crafted blowguns to kill monkeys and birds. After inserting a dart the hunter points the tube vertically, takes a deep breath then blows the dart from the tube. Assume the event occurs without friction. Ignore the friction of the dart sliding inside the gun, the force required to push the air ahead of the dart out of the tube and the drag of the surrounding air as the dart moves upward. The masses of the monkey and dart are 1.8 kilograms and 6.2 grams, respectively. The inside diameter of the blowgun is 0.8 cm. Use the data of the figure.

a) Calculate the least work expended by the hunter.

b) Calculate the average propulsive pressure of discharge of the dart.

c) If the monkey is hit (with the dart fired as usual) What increase of energy does the monkey experience?

BLOWGUN: In the Amazon forrest hunters use hand-crafted blowguns with poisoned darts to kill monkkeys. After inserting a dart the hunter points the tube vertically, takes a deep breath then blows. Bingo! Monkey for dinner.

PART II: The event of firing a blowgun was studied with the assumption that there was no frictio. Perform a more accurate analysis. Approximate the friction force of the dart moving in the tube as twice its gravity force. The drag force of the dart moving upward through air is approximated as:

EMBED Equation

EMBED Equation

where "C" is an experimentally determined drag coefficient (C= 1.1), "A" is the frontal projected area of the dart (diadart=0.8cm), rho is the density of the air (1.2kg/m3) and V is the speed of the dart. The masses of the monkey and dart are 1.8 kilograms and 6.2 grams, respectively. Apply the First Law with the data of the figures to calculate:

a) The least work expended by the hunter.

b) The average propulsive pressure of discharge required.

c) If the monkey is hit (with the dart fired as usual) What does the First Law tell us?

 

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the monkey is hit (with the dart fired as usual) What does the First Law tell us?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BLOWGUN: In the Amazon forrest hunters use hand-crafted blowguns with poisoned darts to kill monkkeys. After inserting a dart the hunter points the tube vertically, takes a deep breath then blows. Bingo! Monkey for dinner.

PART II: The event of firing a blowgun was studied with the assumption that there was no frictio. Perform a more accurate analysis. Approximate the friction force of the dart moving in the tube as twice its gravity force. The drag force of the dart moving upward through air is approximated as:

EMBED Equation

EMBED Equation

where "C" is an experimentally determined drag coefficient (C= 1.1), "A" is the frontal projected area of the dart (diadart=0.8cm), rho is the density of the air (1.2kg/m3) and V is the speed of the dart. The masses of the monkey and dart are 1.8 kilograms and 6.2 grams, respectively. Apply the First Law with the data of the figures to calculate:

a) The least work expended by the hunter.

b) The average propulsive pressure of discharge required.

c) If the monkey is hit (with the dart fired as usual) What does the First Law tell us?

 

MathType

PRINTMAN

MathType

Times New Roman

Times New Roman

Symbol

Symbol

Times New Roman

Times New Roman

"System

Equation

METAFILEPICT

MathType

PRINTMAN

Equation

METAFILEPICT

MathType

Times New Roman

Times New Roman

Symbol

Symbol

Times New Roman

Times New Roman

"System