Newton's Third Law

Answers

1. What is the action - reaction pair of forces acting on the airfoil as indicated by the arrows? foil deflected upward and flow deflected downward
   
   
2. The weight force is the product of the mass multiplied by the acceleration due to gravity. If a DC-10 commercial passenger jet weighs 200,000 kilograms and gravity is 9.80 m/s², calculate the weight force: 1.96 x 106 N.
   
3. If the DC-10 in the previous question is flying at a constant altitude so that the action- reaction forces are balanced, what is the lift force acting on the jet? 1.96 x 106 N
   
   
4. As the jet in the above question travels at constant velocity, it burns fuel, which decreases its weight to 165,454 kg, a safe weight for landing. In response to this decrease, what is the new lift force acting on the jet when altitude is maintained? 1.62 x 106 N
   
   
5. In a department store, a large fan blows upward, keeping a beach ball at a constant height above it. What exerts the action force on the beach ball? air blown upward by fan
   
   
6. In the example above, what is the reaction force on the beach ball? weight force exerted downward
   
   
7. If the beach ball above weighs 280 grams, what are the magnitude and direction of the action force on the beach ball? 2.7 N upward
   
   
8. When the fan blowing on the beach ball above is turned off, how do the action and reaction forces compare? unbalanced; there is no longer a blowing force, just a weight force
   
   
9. Once the beach ball has landed on the ground, what exerts the action force? the ground pushes up
   the reaction force? the ball pushes down

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