Question
3. To determine the location of his center of mass, a physics student lies on a lightweight plank supported by two scales L = 2.60 m apart
(a) If the left scale reads 284 N, and the right scale reads 133 N, find the student's mass.
42.55 kg (Correct)
(b) Find the distance from the student's head to his center of mass.
________ m
"A Physics 210-HW#9-Sp. x 9 To Determine The Locatic × -> Dwww.webassign.net/web/Student/Assignment-Responses/submit?dep-13701 713 c.) The upper arm bone exerts a force (not shown above) on the forearm. This force must be: size: 222.4 × N, dir: downwards 3. + 214 points | Previous Answers My Notes Ask Your Teacher To determine the location of his center of mass, a physics student lies on a lightweight plank supported by two scales L = 2.60 m apart. (a) If the left scale reads 284 N, and the right scale reads 133 N, find the student's mass 42.55 (b) Find the distance from the student's head to his center of mass 0.47 kg 4. -1 points My Notes Ask Your Teacher A couterclockwise torque of +0.87 N·m is applied to a bicycle wheel of radius 30 cm and mass 0.72 kg. Treating the wheel as a thin ring, find its angular acceleration = rad/s 5. -1.5 points My Notes Ask Your Teacher ) 8:17AM
Explanation / Answer
a) F1+F2-mg=0, then
m = (F1+F2)/g = 48.7258 kg
students weight = 284 + 133 = 417N
mass = 417/9.8 = 42.55kg
b) take moments at 284 end
-F1 * L / 2 + F2 *L / 2 + m g x = 0
x = (F2-F1) L / (2 m g) = (F2-F1) L / (2(F1+F2))
133N x 2.6m = 345.8N x L
L = 1m.
So C of G is 1m from head end