Find the initial acceleration of block B

In summary, the system consists of a negligible mass block B connected to a 1kg particle by a non-stretchable string. The particle is given a horizontal velocity root(8gH) while the system is initially at rest. The initial acceleration of block B is found to be 2g, but this answer seems incorrect. After a short time, the system can be assumed to be on a horizontal plane, neglecting the vertical force of gravity. The acceleration is then found to be zero due to the lack of forces. However, in order for the system to be initially at rest as stated in the question, the 1kg block must be held in place by an external force or the system must have been propelled leftwards and
  • #1
Vivek098
9
0

Homework Statement


a block B of negligible mass is connected to a particle of mass 1 kg with a non-stretchable string. Now the hanging particle is given a velocity root(8gH) horizontally when system is at rest. Find the initial acceleration of block B.

Homework Equations


3. The Attempt at a Solution [/B]
Since Mass of Block is negligible, so Tension in String is Zero. Now for Block A, only force acting is mg in downward direction. So, acceleration of Block A is g in downward direction always. In the initial state, the acceleration of block A is equal to acceleration to Block B since they are directly connected by string. So, acceleration of Block B should be g towards right. But actual answer given is 2g.
 

Attachments

  • Screen Shot 2017-12-06 at 6.04.17 pm.png
    Screen Shot 2017-12-06 at 6.04.17 pm.png
    23.5 KB · Views: 699
Physics news on Phys.org
  • #2
Vivek098 said:

Homework Statement


a block B of negligible mass is connected to a particle of mass 1 kg with a non-stretchable string. Now the hanging particle is given a velocity root(8gH) horizontally when system is at rest. Find the initial acceleration of block B.

Homework Equations


3. The Attempt at a Solution [/B]
Since Mass of Block is negligible, so Tension in String is Zero. Now for Block A, only force acting is mg in downward direction. So, acceleration of Block A is g in downward direction always. In the initial state, the acceleration of block A is equal to acceleration to Block B since they are directly connected by string. So, acceleration of Block B should be g towards right. But actual answer given is 2g.

Try drawing a diagram of the situation after a short time. Hint: where are the two blocks?
 
  • #3
Please see the attachment.
 
  • #4
Vivek098 said:
Please see the attachment.

You need a diagram after the particle has moved somewhat!

Hint: assume the experiment is taking place on the horizontal. I.e. ignore the vertical force of gravity. What do you get then?

PS The answer of ##2g## looks wrong to me.
 
  • #5
PeroK said:
You need a diagram after the particle has moved somewhat!

Hint: assume the experiment is taking place on the horizontal. I.e. ignore the vertical force of gravity. What do you get then?

PS The answer of ##2g## looks wrong to me.
The acceleration is zero since there are no forces.
 
  • #6
Vivek098 said:
The acceleration is zero since there are no forces.

Are you sure? That means the block won't move?
 
  • #7
PeroK said:
Are you sure? That means the block won't move?
How could be system initially at rest as mentioned in question. How block b will hold the tension produce in string by 1 kg block?
 
  • #8
Abhishek kumar said:
How could be system initially at rest as mentioned in question. How block b will hold the tension produce in string by 1 kg block?

The 1kg block must be held in place by some external force: it perhaps ought to have been shown at the edge of a small supporting platform.
 
  • #9
PeroK said:
The 1kg block must be held in place by some external force: it perhaps ought to have been shown at the edge of a small supporting platform.
May be
 
  • #10
PeroK said:
The answer of 2g looks wrong to me.
Agreed. Should more than double that.
PeroK said:
The 1kg block must be held in place by some external force
Or just instantaneously at rest, the two blocks having previously been propelled leftwards and upwards respectively.
 
  • #11
haruspex said:
Or just instantaneously at rest, the two blocks having previously been propelled leftwards and upwards respectively.

Slightly trickier for a lab technician to arrange!
 

Related to Find the initial acceleration of block B

1. What is the meaning of "initial acceleration" in this context?

The initial acceleration of block B refers to the rate at which block B begins to move or change its speed when a force is applied to it for the first time.

2. How is the initial acceleration of block B calculated?

The initial acceleration of block B can be calculated by dividing the initial velocity of the block by the time it takes for the block to reach that velocity.

3. What factors can affect the initial acceleration of block B?

The initial acceleration of block B can be affected by the magnitude and direction of the applied force, the mass of the block, and any external forces such as friction or air resistance.

4. Can the initial acceleration of block B change over time?

Yes, the initial acceleration of block B can change over time if the magnitude or direction of the applied force changes, or if other external forces come into play.

5. Why is it important to find the initial acceleration of block B?

Finding the initial acceleration of block B is important because it helps us understand the motion and behavior of the block in response to applied forces. It can also be used to predict the future motion of the block and determine the amount of force needed to achieve a desired acceleration.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
2
Replies
52
Views
801
  • Introductory Physics Homework Help
2
Replies
35
Views
2K
  • Introductory Physics Homework Help
Replies
12
Views
984
  • Introductory Physics Homework Help
Replies
2
Views
741
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
11
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
3K
  • Introductory Physics Homework Help
Replies
8
Views
1K
  • Introductory Physics Homework Help
Replies
23
Views
2K
Back
Top