# Homework Help: Newton's laws of motion -- Constaint motion

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1. Jun 28, 2017

### Vv anand

1. The problem statement, all variables and given/known data
In the following diagram a massless pulley is pulled by a constant force of magnitude P. There is no friction between the block and the floor. The acceleration produced in the block if mass m is? PIC ATTACHED

2. Relevant equations
Took a1/2=a2 where a1 is accn of block and a2 is accn of pulley since a3 that is accn of the string attached to wall is 0

3. The attempt at a solution
tried solving by taking acceleration but found that pulley is massless so I'm pretty confused atm and pls help me and clear my doubt

#### Attached Files:

• ###### IMG_20170627_170356.jpg
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2. Jun 28, 2017

### Vv anand

Answer is P/2M but i end up getting P/M

3. Jun 28, 2017

### Staff: Mentor

If P is the force pulling the pulley, what is the tension in the wire?

4. Jun 28, 2017

### Vv anand

That is not given sir...and P is the force pulling pulley

5. Jun 28, 2017

### Staff: Mentor

Have you drawn a free body diagram of the pulley, or do you feel that you have advanced beyond the point where you need to use free body diagrams? From a free body diagram of the pulley, what are the three forces acting on the (massless) pulley?

6. Jun 28, 2017

### Vv anand

Yes sir P is the force on the pulley,
Tension is not given..I calculated it as MG as There does not exist any other force that exists on M (surface is frictionless)

7. Jun 28, 2017

### Vv anand

I hv drawn it..just had the doubt that Is P=2T?

8. Jun 28, 2017

### Staff: Mentor

9. Jun 28, 2017

### Staff: Mentor

You don't think that the wire tension is acting on the mass?

10. Jun 28, 2017

### Vv anand

Of course sir

#### Attached Files:

• ###### IMG_20170628_183906.jpg
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11. Jun 28, 2017

### Vv anand

Yes sir i just uploaded the fbd

12. Jun 28, 2017

### Vv anand

Is it correct...By doing this i get the answer

13. Jun 28, 2017

### Staff: Mentor

So, as you have found from your fbd, P=2T. So, ma=T=P/2

14. Jun 28, 2017

### Vv anand

Wow!....I calculated it myself... Hats off to ur organization sir...Really obliged to get to know about ur organization ..Will surely recommend it to others