MY CART (5)

Use Coupon: CART20 and get 20% off on all online Study Material

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price: Rs.

There are no items in this cart.
Continue Shopping
Menu
Grade: 12
        

A man stands at the centre of a circular platform holding his arms extended horizontally with 4kg block in each hand. He is set rotating about a vertical axis at 0.5 rev/s.The moment of inertia of the man plus platform is 1.6kg-m2, assumed constant. The blocks are 90 cm from the axis of rotation. He now pulls the blocks in toward his body until they are 15 cm from the axis of rotation. Find the initial and final kinetic energy of the man and the platform

7 years ago

Answers : (1)

vikas askiitian expert
509 Points
							

moment of inertia of blocks = 2Mr2 =2*4*(0.9)2 (r=0.9m)

                                       =6.48kg-m2

moment of inertia of platform + man = 1.6                       (given)

total moment of inertia (I)= 6.48+1.6=8kg-m2

w = 2pi(f) = 2pi(0.5)=(pi) radsec-1

kinetic energy(initial) = Iw2/2 = 8(pi)2 /2=4pi2 =39.4J          (approx)           (ans1)

finall blocks are at 15cm from axis of rotation ....angular velocity of blocks is changed now

applying conservation of angular momentam

IW = If Wf  .................1

kinetic energy final = IfWf2/2

                           =If (IW/If)2 /2                       (from eq 1)

                           =(I/If)(IW2/2)

                           =(I/If) (KE)i=(I/If) (4pi2)

If = 1.6 + 2Mr2 = 1.6+.18=1.8                             (r =0.15m)

I/If = 4.44 so

final kinetic energy = 4.44*4pi2 =175J     (approx)                 (ans2)

approve my ans if u like

7 years ago
Think You Can Provide A Better Answer ?
Answer & Earn Cool Goodies


Course Features

  • 101 Video Lectures
  • Revision Notes
  • Previous Year Papers
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Test paper with Video Solution


Course Features

  • 110 Video Lectures
  • Revision Notes
  • Test paper with Video Solution
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Previous Year Exam Questions


Ask Experts

Have any Question? Ask Experts

Post Question

 
 
Answer ‘n’ Earn
Attractive Gift
Vouchers
To Win!!! Click Here for details