Name:_________________________



Name:_________________________________________________________ Physics

Date:_______ Pd:________

Force Table Lab (worth 20 points)

Purpose: Apply the laws of vector addition to find resultant and equilibrant forces.

Background: A system is in equilibrium when the sum of the forces acting on it is zero. A force table can be used to create an equilibrium condition. Equilibrium is achieved when the ring is directly over the center of the circle.

Materials:

one force table per group

assorted masses

ruler, graph paper, tape, protractor

Goals:

Each student will:

• select a new set of masses and

angles to create equilibrium on their force table

• create a scale drawing of the forces

Procedure:

1. Use a force table with three strings.

2. Each student will use different angles and different masses. Each string should have a different amount of mass.

3. Adjust masses until the ring is perfectly centered and hovering over the bolt.

4. Record angles and masses.

5. Create a vector diagram with all the elements described below. You diagram should mostly fill up a sheet of graph paper, so choose your scale wisely.

The vector diagram should contain the following elements:

1. a title ( 1 point)

2. name of student (1 point)

3. boxed scale of drawing (2 points) ex: 1.0 cm = 0.1 N

4. label vectors A & B (2 points)

5. label the resultant of forces A and B, found graphically (2 points)

6. label the equilibrant (the third force) (2 points)

7. label all four vectors with the correct newtons (4 points)

8. calculate the percent error for the magnitude of the resultant (2 points)

9. neatness (4 points)

Helpful Information:

• The accepted value for the resultant is equal and opposite to the magnitude of the equilibrant.

So, percent error for the magnitude of the resultant :

percent error = length of resultant – length of equilibrant x 100

length of equilbrant

• To convert grams to newtons: 1 g = 0.0098 N

Procedure:

1. Set up the force table with your paper secured on top.

2. Hang four masses of your choice and adjust the angles of the strings until the ring is over the center and equilibrium has been achieved.

3. In pencil, sketch the quantity and direction of your masses.

4. Remove your masses and paper. Decide on a scale for your drawing (ex: 1 mm = 1 gram; 1 cm = 1 gram).

5. Create your drawing. Use a ruler and protractor. Be neat.

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Force B

Force A

Pick one force to be the equilibrant.

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