badge image

Enroll For Free Now & Improve Your Performance.

×
User Icon
User Icon
User Icon
User Icon
User Icon

Thank you for registering.

One of our academic counsellors will contact you within 1 working day.

Please check your email for login details.
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: upto college level

                        

A student attaches a ruler to a block of wood sitting on a horizontal surface as shown in Fig. 3-20a. The surface exerts a large frictional force on the block. A nail is fastened at the 0-in, mark. The student pulls the rubber band tight at the 5-in . mark; he then pulls it tighter and when it reaches the 8-in. mark, the block of wood just starts to move (Fig. 3-20b). Before the block begins to move, the net force on the block when the rubber band is stretched 7 in. is (A) greater than (B) equal to (C) less than (D) unrelated to the net force on the block when the rubber band is stretched 6 in.

5 years ago

Answers : (4)

Navjyot Kalra
askIITians Faculty
654 Points
							The correct option is (C) less than.
The block of wood just starts to move when rubber band reaches the 8-in mark. Since the block of wood will not move in between the mark 5-inches to 8-inches, therefore the magnitude of applied force (Fapp) on the block of wood is smaller than the frictional force (f).
So the net force acting on the block of wood (Fnet) when the rubber band is 7-mark is
Fnet = f- Fapp
or,
Fapp = f -Fnet
Therefore the net force on the block when the rubber band is stretched 7 in. is lesser than the net force on the block when the rubber band is stretched 6 in.
From the above observation we conclude that, option (C) is correct.
5 years ago
Paarth Arkadi
22 Points
							
I think the option is B since the frictional force( static friction )  adjusts itself to the applied force . Hence since the body is at rest  if the applied force is 1N then friction force is 1N , if  applied force is 0.5 N the frictional force is 0.5N  assuming the maximum value( limmiting value ) of force is 2N and the object does is at rest. Since the net force is asked and not the applied force hence the net force remains zero till the block does not move
5 years ago
Paarth Arkadi
22 Points
							
I think the option is B since the frictional force( static friction )  adjusts itself to the applied force . Hence since the body is at rest  if the applied force is 1N then friction force is 1N , if  applied force is 0.5 N the frictional force is 0.5N  assuming the maximum value( limmiting value ) of force is 2N and the object does is at rest. Since the net force is asked and not the applied force hence the net force remains zero till the block does not move
5 years ago
Paarth Arkadi
22 Points
							
I think the option is B since the frictional force( static friction )  adjusts itself to the applied force . Hence since the body is at rest  if the applied force is 1N then friction force is 1N , if  applied force is 0.5 N the frictional force is 0.5N  assuming the maximum value( limmiting value ) of force is 2N and the object does is at rest. Since the net force is asked and not the applied force hence the net force remains zero till the block does not move
5 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