Physics+1200+Lab-8

Physics 1200 - Lab#8 Page 3 of 7 Activity 2: Static equilibrium of the meter stick a) Predict where a 90 g mass must be hung on the meter stick to keep it horizontal. Meter stick has holes at 30 cm mark and 60 cm mark. Insert the dowel at 30 cm hole on the meter stick. Determine at what position on the meter stick you need to hang the 90 g mass (including hangar mass) to maintain a horizontal orientation. Draw a free-body diagram of the meter stick showing ALL forces acting on the meter stick and their positions in the Fig-2 above. Indicate your choice of axis of rotation. Verify if the meter stick maintains horizontal equilibrium by hanging the 90 g mass at the calculated position. Does it balance? Yes No b) Repeat the above procedure by attaching the meter stick to the dowel at 60 cm position, and predict where a 70 g mass (including hangar) must be hung on the meter stick to keep it horizontal. Does it balance? Yes No 0cm O E tty am so cm 0

Physics 1200 - Lab#8 Page 6 of 7 Fig-5: Torque, τ = r × F × sin θ (torque is identified with a positive or negative sign. If a torque causes counter-clock-wise acceleration it is positive, and for clock-wise acceleration it is negative). Collect the following values for each force from the above free-body diagram and enter in the table below to calculate the ± torques they produce. r is the distance from axis of rotation to the point where the force is applied. F is magnitude of the force. θ is the angle between r and line of F . Exercise 2: Solve the problem and determine the position of the pirate that will keep the setup in balance (hint: when the setup is in balance the net torque = 0). At what position will you place the pirate? _________________________ Distance, r cm Force, F (gm-w) Angle, θ Torque, τ (cm·gm -w) = ± r × F × sin θ Plank Seagull Dowell Pirate 350-g mass Mfs of t dog Mag 10 134 1800 1340 25 50 2700 1240 0 149 1730 710 46 150 2700 6226 30 350 650 9516 45cm from the pivot point