Question

Two masses 6 kg and 4kg are connected by massless flexible and inextensible string passing overmassless and frictionless pulley .The acceleration of centre of mass is (g=10m/sec2)1)0.4 m/sec22)2m/sec23)50 m/sec24)zero

Answer 1

Given

• Mass = 6kg & 4kg
• They are connected by an inextensible string passing over a massless & frictionless pulley

To Find

• Acceleration

Solution

☯ ΣFx = ma_x

• Due to its higher mass, the 6 kg block would go down and the 4 kg block would go up

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✭ According to the Question :

Case 1:

⇒ 60 - T = ma

⇒ 60 - T = 6a -eq(1)

Case 2:

⇒ T - 40 = ma

⇒ T - 40 = 4a -eq(2)

Sub eq(2) from eq(1):

60 - T = 6a

(-) -40 + T = 4a

━━━━━━━

20 = 2a

━━━━━━━

⇒ 20 = 2a

⇒ a = 2 m/s²

∴ The correct answer is Option 2 [2 m/s²]

Answer 2

Given :-

Two masses 6 kg and 4kg are connected by a massless flexible and inextensible string passing over massless and frictionless pulley

To Find :-

Acceleration of centre of mass is

Solution :-

We know that

F_(Net) = ma_x

On Mass 1

Net force = 6 × 10 - T

Net force = 60 - T

Force = ma

Force = 6a

On Mass 2

Net force = T - 4 × 10

Net force = T - 40

F = ma

F = 4a

Net force 1 + Net force 2 = Force 1 + Force 2

60 - T + T - 40 = 6a + 4a

60 - 40 = 10a

20 = 10a

20/10 = a

2 = a

Hence,

Acceleration is 2 m/s²