The puck in the figure has a mass of 0.11 kg. Its original distance from the cen

Question

The puck in the figure has a mass of 0.11 kg. Its original distance from the center of rotation is 35 cm, and the puck is moving with a speed of 70 cm/s in a circle. The string is pulled downward until the center of rotation has moved to r=14 cm. The table is effectively frictionless. 1. What is the original angular momentum of the puck? 2. What is the angular momentum after the puck has moved to r=0.14? 3. What is the original moment of inertia? 4. What is the moment of inertia after the puck has reached r=0.14?

Explanation / Answer

a) L = m . v . r = 0.11 . 0.7 . 0.35 = 0.02695 kgm^2/s b) Same - no torque has been applied c) Ii = mr^2 = 0.14 . 0.02695 ^2 kgm^2=1*10^-4 d) Same again with different radius = Iii e) Work done = Final KE – original KE Use angular momentum stays the same to work out the final velocity of the puck. Plug that in to 1/2 . m . v^2 to get the final energy . Work out the original energy and take them away

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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