Force Table Lab Design

                                                                        Finding Resultant and Equilibrant

                                                                        (to do at end of Ch3 prior to Ch4)

Definitions to know:

Vector quantity-has magnitude plus direction, i.e. 40 km  [N37E], 30N [S38W]

So far, vectors can be displacements (d), velocities (v), accelerations (a), and Forces (F).

Scalar-just magnitude, no direction, i.e. 25 m/s, 25N (Newtons)

Magnitude-physical quantity and unit; i.e. 40 Newtons, 25 m/s, 80 km, 9.8 m/s2

Direction-i.e. E25S, East, NW

Resultant-the single vector which represents the sum of two or more vectors.

Equilibrant-equal in magnitude, but opposite in direction of the resultant. 

 

Force is equal to mass (kg) * acceleration (m/s2), F=ma, and forces are vectors with magnitude and direction. 

Weight (Wt) is a force and Wt=mg        Example, 50g=0.05kg*9.8m/s2=0.49N

Forces have units of kg * m/s2, otherwise known as a Newton (N).

 

The force table allows for the visual and physical representation of force vectors, and may not be very accurate when compared to math calculations.  Forces can be added to find resultants, just as displacement, velocity, and acceleration vectors are added. 

  1. Using the force table, find the resultant and equilibrant of the vectors below.  
  2. First convert all masses to Newtons, and add in the 15g mass for the mass hangers.  Sketch the vectors, on separate paper using a scale of 0.1 N = 1 cm.   Use a protractor and straight edge for accurate/neat drawings. 

·        Graphically draw the vectors from the center point of the table.  This is called a free-body diagram. 

·        Do the mathematical calculations to prove your results; use components.  Use the force table to visually verify your results.  Remember the table is not accurate. 

    1. 3 vectors, 40 degrees apart with hanging masses, empty hanger (15g) in the middle and 20g (+15g) on each side.
    2. 3 vectors, 80 degrees apart with hanging masses, 50g (+15g) in the center and 20g (+15g) on each side. 
    3. Now, in one problem, design three original vectors to resolve, with each a different magnitude and angle.  Sketch the vectors showing the resultant and equilibrant as done for the above vector sets.  (Show mathematical calculations to prove your results.)  Careful, this resultant and equilibrant will not overlap on the middle vector.  You will have to calculate the direction on this one. 

 

*****On all three free-body diagrams, indicate resultant and equilibrant vectors with colored pencils so distinguishable from original vectors.  Write the scale on the drawings of 0.1N-1 cm.  May have to modify this for the problem you design to accommodate the length of the vectors, just note the new scale.