A student investigates the extension of a silicone rubber cord when slotted masses are suspended from it.
Identify the three additional items of apparatus from the list below that the student must use to carry out this investigation (assume they already have the silicone rubber cord and the slotted masses):
The table below shows the student's results. The student uses g=9.8 N/kgg = 9.8\text{ N/kg}g=9.8 N/kg to calculate the gravitational force of each mass.
| Mass in g\text{g}g | Force in N\text{N}N | Extension in mm\text{mm}mm |
|---|---|---|
| 000 | 000 | 0.00.00.0 |
| 100100100 | 0.980.980.98 | 4.24.24.2 |
| 200200200 | 1.961.961.96 | 7.87.87.8 |
| 300300300 | Missing | 10.810.810.8 |
| 400400400 | 3.923.923.92 | 13.213.213.2 |
| 500500500 | 4.904.904.90 | 15.015.015.0 |
State the value of the missing force in the table.
Describe how the extension of the silicone rubber cord changes as the force increases.
Explain whether the silicone rubber cord obeys Hooke's Law.