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Home Minds On Newton's Laws Mission NL11 Air Resistance Help Help 3

Mission NL11 Air Resistance

The Question

The diagrams below represent the free-body diagrams for different skydivers at various moments during their fall. Rank the diagrams in order of increasing acceleration (magnitude only), beginning with the smallest. ...

Game Plan

The acceleration of an object is the ratio of the net force that is exerted upon it to the mass of the object (see Formula Frenzy section). If given a free-body diagram with all the individual forces listed, the net force can be calculated by adding the forces as vectors. An up force would serve to cancel or partially cancel a down force. The mass can be calculated from the force of gravity (see Formula Frenzy section). So the best approach to this problem involves the following steps:
 
  • Calculate the net force from the values of the individual forces.
  • Calculate the mass from the value of the force of gravity.
  • Calculated the acceleration as the ratio of net force to mass.
  • Repeat for all four objects and then rank them accordingly.

Formula Fix

The relationship between net force (Fnet), mass (m) and acceleration (a) is expressed by the equation:
 
a = Fnet/ m


The mass of an object is mathematically related to its weight by the equation:
 
Weight = Fgrav= mass • g
 
where g is the acceleration caused by gravity alone. The value of g on Earth is 9.8 m/s/s (approximately 10 m/s/s).

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