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: 11
        a bullet fired on to a wooden plank.in penetrating trough the plank it lose 10% of its kinetic energy. how many planks are required just to stop the bullet?
10 years ago

Answers : (2)

Ramesh V
70 Points
							

as from the wuation. it says bullet loses (10)-1/2 of velocity upon penetration into each plank

I feel that this data is not enough. A lot more data is required like

we need to know the minimum velocity required to pass through a single plank.??

how far away are you shooting?
how thick are the planks?
how far apart are the planks?

definitely not enough info to answer. but technically the least that COULD stop it if the variables are right is 2 or 3.

10 years ago
AskIITians Expert PRASAD IIT Kharagpur
18 Points
							

Let thickness of one plank be = d.

KE1 = 0.5*m*v2

KE2 = 0.5*m*v 22  = 0.9 *0.5*m*v2    So,   v 22  = 0.9 *v2   .

Let us calculate deceleration produced by one plank using  v 22  = v 12  -  2*a*d

So,   2*a =  (0.1*v2) / (d).

Final velocity  =  0 m/s.

So, 0 = v 2  -  2*a*d1 

d1 =  v 2 / (2*a)  = v 2 / ((0.1*v2) / (d)) = 10*d.

So, 

d1 =   10*d.

Since one Plank is of thickness d,  10*d is thickness of 10 planks.

So,   10 planks are required just to stop the bullet.

 

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


Course Features

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


Course Features

  • 18 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