Es2 Exp 1 - Centre Of Gravity_1012.pdf

Engineering Science Worksheets FORCES KIT ES2 1. CENTRE OF GRAVITY

Name Date Course/Year/Group

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ES2 Worksheet

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ES2 Worksheet

Centre of Gravity

Centre of Gravity Aims To compare two methods of finding centre of gravity of thin plates.

Experiment Setup As shown in Figure 1, fix the parts to the Work Panel. Count the holes in the Work Panel if you need to make sure everything fits correctly. Your teacher may have already cut the cord to the right length for you.

Plummet Arm

Make sure the cord passes through the centre of the plastic sucker. Sucker Assembly

Figure 1 Experiment Setup

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Centre of Gravity

ES2 Worksheet

Experiment Procedure Part A - Using a Plummet

NOTE

The exact amount of weights on the Weight Hanger is not important, as the Weight Hanger only works as a plummet.

1. Read the Guidance Notes (supplied). 2. Attach one of the shapes to the suction cup and allow it to swing until it rests in its natural position. 3. Use your marker pen to mark on the shape where the plumb line passes over its front (see Figure 2). 4. Take the shape off the suction cup and use a straight edge (the long side of the rectangle or L shape) to draw a line between your marks (the line of action). 5. Refit the shape back on the suction cup, so the suction cup holds a different part of the shape. Repeat the procedure. 6. Where your two ‘lines of action’ cross should be the centre of gravity of the shape. Mark this point with an ‘X’. 7. Repeat for all the shapes. Notice that the centre of gravity for the L shape is not actually on the plate (see Figure 3).

Experiment Procedure Part B - Simple Drawing Method Use the half-size blank diagrams (Figures 4 and 5) to draw the lines of symmetry and centre of gravity (if possible) for each shape and compare with that found from experiment. For the irregular shape, try to divide it into standard shapes (triangles or rectangles) and find the centre of gravity of each standard shape, then join these centres to give an area within which lies the centre of gravity.

Questions and Conclusions Which method is best for each shape?

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ES2 Worksheet

Centre of Gravity

Centre of gravity

Figure 2 Drawing the Lines of Action to Find the Centre of Gravity

Centre of gravity

Figure 3 Centre of Gravity of L Shape

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Centre of Gravity

ES2 Worksheet

Circle

Note: Drawings are Half-size

Rectangle

Semicircle

Figure 4 Blank Drawings of the Shapes

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ES2 Worksheet

Centre of Gravity

Irregular Shape

Note: Drawings are Half-size Triangle L shape

Figure 5 Blank Drawings of the Shapes 8

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Notes

ES2 Worksheet

Notes

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