A 20 cm x 40 cm door sign (20 kg) is hung from the ceiling with two 30-cm rigid

Question

A 20 cm x 40 cm door sign (20 kg) is hung from the ceiling with two 30-cm rigid steel bars
(massless) as shown. A putty of 100-grams, traveling at 20 m/s, struck the center of the sign and
stuck there. What is the max angle this sign will swing up to? (Moment of inertia of rotating a
rectangular plate along its edge is = 1/3 Ma^2).

A 20 cm times 40 cm door sign (20 kg) is hung from the ceiling with two 30-cm rigid steel bars (massless) as shown. A putty of 100-grams, traveling at 20 m/s, struck the center of the sign and stuck there. What is the max angle this sign will swing up to? (Moment of inertia of rotating a rectangular plate along its edge is = 1/3 Ma^2).

Explanation / Answer

Moment of intertia of plate=ma^2/3+md^2=2.067kgm^2

moment of inertia after putty has stuck=2.083kgm^2

Conserving energy,

0.5mv^2=Mgh

h=0.1015cm

Rise=L(1-Cos(theta))

L=0.4m

SOlving for theta,

theta=41.74 degrees

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.