Question

Two blocks A and B of mass 2kg and 3 kg respectively are connected by a light string are placed on a smooth horizontal surface as shown in the figure.If the block A is pulled by a force of F=10 N .The tension in the string connecting them is A) 12 N B) 10 N C) 6 N D) 4 N

Answer 1

Solution :

⏭ Given:

✏ Two blocks A and B of mass 2kg and 3kg are connected by a light string are placed on a smooth horizontal surface.

✏ Block A is pulled by a force of 10N

⏭ To Find:

✏The tension in the string...

⏭ Concept:

✏ First we have to find out acceleration of the system, after that we can calculate Tension force in the string.

⏭ Diagram:

✏ Please, see the attached image for better understanding..

⏭ Calculation:

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• Acceleration of system

✏ Fnet = (m1 + m2) × a

✏ 10 = (2 + 3) × a

✏ 10 = 5a

✏ a = 2m/s$^2$

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• Tension force in the string

✒ As per FBD of B block, it is clear that

✏ T = m2a

✏ T = 3 × 2

✏ T = 6N

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✒ Tension in the string = 6N

Answer 2

Given:

Mass of A = 2kg

Mass of B = 3 kg

Force on block A = 10 N

To find:

Tension in the string pulling the blocks

Concept:

First of all, refer to the attached photo . Try to identify all the forces Acting on the block and draw the FREE-BODY DIAGRAM of all the blocks.

Calculation:

Let tension be T and acceleration be a.

For 2 kg Block :

$\huge{ \green{10 - T = 2a}}$

For 3 kg Block :

$\huge{ \green{T = 3a}}$

Adding up the equation :

$\huge{ \bigstar{ \red{10 = 3a + 2a}}}$

$\huge{ \implies \red{10 = 5a}}$

$\huge{ \implies \red{a = 2 \: m {s}^{ - 2} }}$

Putting value of a in 2nd equation :

$\huge{ \green{T = 3a}}$

$\huge{ \green{ \implies T = 3 \times 2}}$

$\huge{ \green{ \implies T = 6 \:N }}$

So final answer :

T = 6 N