Starter What is the spring constant for this spring? What is the meaning of the y-intercept?

Starter Hooke’s Law If a 1kg mass stretches a spring 2.5cm, what mass would stretch it 10cm?

Hooke’s Law for Springs The force required to stretch a spring is directly proportional to how much it is stretched, or : F = kx F = stretching force in Newtons x= stretch in meters k = the spring constant in N/m

Example When a .5kg mass is hung on a spring, it stretches .25m. 1. What is the spring constant? k = F/x = mg/x = .5(9.8)/.25 = 19.6 N/m 2. How much would a 2kg mass stretch the spring? x = F/k = 2(9.8)/19.6 = 1.00m

Hooke’s Law F =kx If you plot the stretching force on the y axis, and the amount of stretch on the x axis, what will the plot look like? What does the slope represent? Slope = k

Practice - Hooke’s Law P m (kg) x(m) F (N) 0.00 0.00 .050 .045 .441 0.00  .050 .045 .441 0.100 0.090 .980 P

Elastic Forces - Hooke’s Law F = kx k = 10.9 N/m

Application - Springs A Design an experiment to determine the spring constant for: 2 of the color coded springs 1 of the silver springs. A rubber band Make a F vs. x graph for each with 5 data points. Show a best fit line and determine the equation and k. A

Sample Data table Spring Color ______________ Trial m (kg) x(m) F (N) Plot on x-axis Plot on y-axis Trial m (kg) x(m) F (N) 1   2 3 4 5

Question Did the rubber band obey Hooke’s Law? Explain.

Lab Report Checklist Starter Data Tables (4) F vs. x Graphs (4) with slopes Experimental k values (4) Question Connection Summary

Connection C What real life applications of Hooke’s Law have you observed? C

EXIT E Summarize your experiment including the objective, the procedure, the results, and reasons for error. E