Hooke Laws.docx

Apparatus Helical steel spring with supporting stand and scale, rubber band, set of slotted weights with hanger

Procedure 1. A table rod with a rod clamp was installed near its top. A helical spring was suspended from the spring stand. (Figure 1) 2. A 10 g weight hook was attached to the spring. The initial mass of 10 g [m] was recorded. The parameter m will represent the total mass on the spring. 3. The meter stick was placed vertically alongside the hanging mass. The elongation of the spring was measured and was recorded it as x1. Always be sure to measure starting at the same place, either on the table or on the clamp. 4. A 10 g slot mass was added to the hook and was recorded m2 (20 g). The meter stick was readed and recorded x2. Repeat, findings x3, x4, x5, and x6 with total masses 30 g, 40 g, 50 g, 100 g, 150 g and 200 g. All the masses and elongations was recorded. (Figure 2) 5. This procedure was repeated for both helical spring. 6. A piece of band of about 50 cm length was cutted of,to determine the characteristic curve of the rubber band. 7. Both ends of the rubber band was tied to small loops with silk thread. 8. One loop was slipped onto the holding bolt and the weight holder was suspended from the other loop. In the same way as for the helical springs, forces (weights) was increased in steps of 10 g up to a maximum of 200 g. 9. The process was reversed by unloading the same load. 10. The masses you had recorded in grams was converted to kilograms. Also the distance measurements made in centimeters was converted to meters.

Figure 1 : A helical spring is suspend from the spring stand

Figure 2 : Measurement of the elongation of the helical spring

Results Trial

Mass (in grams)

Mass (in kilograms)

Force (in newtons)

1 2 3 4 5 6 7 8 9 10 11 12

0 10 20 30 40 50 60 70 80 90 100 110

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11

0.000 0.098 0.196 0.294 0.392 0.490 0.588 0.686 0.784 0.882 0.980 1.078

Note : units conversion 1gm = 0.001 kg 1 kg = 9.8 N 1 Newton = 0.101 kg 1 Newton = 101.9 g 1 gm = 0.0098 Newtons 1 m = 100 cm

Elongation (in centimeters) 24.4 27.3 30.5 34.0 37.0 39.8 43.3 46.7 49.5 52.6 56.1 59.3

Elongation (in meters) 0.244 0.273 0.305 0.340 0.370 0.398 0.433 0.467 0.495 0.526 0.561 0.593

Extension distance, ΔX (in m) 0 0.029 0.061 0.096 0.126 0.154 0.189 0.223 0.251 0.282 0.317 0.349

K = F/X

0 3.380 3.213 3.063 3.111 3.181 3.111 3.076 3.124 3.128 3.091 3.088

2. From the graph the helical spring constant is 0.0948 N/m. 3. Elastic bands do not obey Hooke’s Law. As the force applied is not proportional to the extension of the band. Typically, a fair amount of stress is required on stretching to produce a small amount of strain. But eventually, less stress is needed for the same amount of strain. This is because the atoms in the elastic band have more kinetic energy so can be extended further. Helical spring works on the principle of Hooke’s Law. Hooke’s Law states that within the limit of elasticity, stress applied is directly proportional to the strain produced.

4. The precautions that we can made during this experiment is , to make sure that all the equipment that are going to be use are in good condition and have been properly calibrated to fit the experiment. Next, make sure the person who manages to add the mass into the hanger are not stretches the spring. Make sure that there are very small of air resistance during the experiment to prevent the spring from swinging and let it on only oscillation. Make sure that the eyes are perpendicular to the scale of the measurement instruments to avoid this type of error. Make sure that we take the record in two or three decimal places in data reading so that the data will be more accurate.

1.2

Force vs distance graph

Force, F (Newtons)

1 0.8 0.6

helical spring constant,K = 0.0948 N/m y = 0.0948x - 0.1658

0.4 0.2 0 -0.2