Spring Surprise! #1 Name _______________. 1) Prediction: The harder you pull on a spring, the longer you make it. What will a graph of the Force vs. Length of spring look like? Explain. F F x A). F F x B) x x C) D) 2) Observation: Apply a force by attaching masses to the spring. Calculate the force in N using F = mg. a) Measure the increase in length in metres. Make five well-spaced measurements and graph your results. b) Draw a best-fit line and calculate the slope. Include units and appropriate significant digits. c) The slope is called the Hooke’s Law constant and is usually given the symbol k. What is a simple adjective that is equivalent to k? c) Hooke’s law is F = k x. What is the difference between x and x? 3) Practise Calculation: A spring has a Hooke’s law constant of 72 N/m. a) Calculate how much its length will increase if you add 375 g to it. b) You want the spring to stretch by 12.2 cm. Calculate how much mass you will need to add to it. c) You want the spring to stretch by 72 cm. Calculate how much mass you will need to add to it. 4) Practise Contest: Take a different spring. a) Calculate the spring constant as quickly and accurately as possible. Show your measurements and calculations neatly below. b) Calculate how far it will stretch if ______ g is added. Mark where the bottom of the hook will go on your board. c) Place the mass on the hook and mark where the bottom of the hook did go. What was the percentage difference between the predicted stretch and the measured length? d) How can you improve your technique? 5) Contest: Take another spring. On another piece of paper, write your names, and neat measurements and calculations for the spring constant – including units and the correct number of significant digits. Mark where the bottom of your spring lies on your board. Show it to the teacher. You will be told what mass will be hung on the spring. Make neat calculations on the paper of how much it will stretch by and mark the new position on your board. When ready, the teacher will bring the mass and observe how successful you are.