1) The document provides instructions for students to work through calculating forces on an object suspended at an angle from two spring scales. 2) Students will take turns drawing and updating a force diagram on a whiteboard to show the problem set up and identify force components. 3) Using trigonometry relationships, students will calculate the magnitude of tension and gravitational forces acting on the object at a 78 degree angle. 4) From the balanced force diagram and equation, students will calculate the mass of the object.

1. Calculating Force at Angles other than 0* and 90*

2. Rules of This Activity#1 All students must perform all of the work of the activity in their science journals, even the work that you also did on the large white board!#2 All first row students will begin the activity on a large whiteboard which will then be passed to the student seated behind them when their assigned work is completed.#3 All previous work is to remain on the white board. #4 The board will continue to passed to the student in the next row as each student completes their assigned work. The column of students to correctly complete the work first will be declared the winners.

3. The Problem

4. Working the ProblemRow#1 Draw a force diagram of the object suspended from two spring scales that is set up on the teacher’s desk. Remember to use the four steps (C of M, long term forces, contact forces, labeled axes) in creating a force diagram!

5. Working the ProblemRow #1 Draw a force diagram of the object suspended from two spring scales that is set up on the teacher’s desk.Row #2 Use SOH-CAH-TOA, to find the magnitude of the T1 , T2x , T2y and Fgcomponents. Show all of your work.

6. Working the ProblemRow #2 Use SOH-CAH-TOA, to find the magnitude of the T1 , T2x , T2y and Fgcomponents. Show all of your work.Row #3 Draw a “clean” force diagram, breaking Fg, T1 and T2 into their x and y components.Again remember to use the four steps (C of M, long term forces, contact forces, labeled axes) in creating a force diagram!

7. Working the ProblemRow #3 Draw a “clean” force diagram, breaking Fg, T1 and T2 into their x and y components. Row #4 Using F = ma, calculate the mass of the object showing all of your work. When your work is completed, consult with all of the members of your column to decide if the final answer is thought to be correct before submitting it for approval.

8. The Force Diagram yT2 78* T1 (1N) xFg

9. SOH – CAH - TOACOS θ = T2x/T2 and T1 = T2x COS 78* = T2x/T2 (T2) COS 78* = 1N (T2) (0.208) = 1N T2 = 1N/0.208 T2 = 4.8N SIN θ = T2y/T2 SIN 78* = T2y/4.8N (4.8N) SIN 78* = T2y (4.8N) (0.978) = T2y 4.69N = T2y

10. The “Clean” Force Diagram yT2y 4.69N x T1 1N T2x 1NFg

11. F = maFg = may and T2y = may 4.69N = may 4.69N = (m)(9.8 m/s2) 4.69N/9.8 m/s2 = (m) 4.69N/9.8 m/s2 = .478 kg Now, lets put the object on the balance!