Question

The three blocks shown move with constant
velocities. Find the velocity of block A and B. Given
Vp =10m/s1. V = 2 m/s 1
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lauvetem shown​

Answer 1

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Answer 2

Concept:

Application of relative motion will be used here, which is that Motion is always relative because it always occurs inside a certain frame of reference.

Given:

Pulley 1 is fixed means the velocity will be 0.

Velocity of Pulley 2 is 10 m/s and going toward upwards

Velocity of Block C is 2 m/s and going toward downwards

Velocities are constant means acceleration is zero.

Find:

Velocity of Block A

Velocity of Block B

Solution:

Negative and Positive sign are just direction indicators

If we observe from the frame of reference of Pulley 1

then Velocity of Pulley 2 will be equal to speed of block A as speed of Pulley 1 is zero.

Velocity of Pulley 2 = Velocity of block A

Velocity of block A = -10 m/s

So speed of Block A is 10 m/s and going towards downward.

If we observe from Pulley 2

By apply the concept of relative motion

Velocity of B wrt Pulley 2 = Velocity of Pulley 2  - Velocity of Block C

Velocity of B wrt Pulley 2 = 10  - 2

Velocity of B wrt Pulley 2 = 8

Now Block B also has 10 m/s velocity in upward direction due to Pulley 1

Net Velocity of B = (10+8) m/s

Net Velocity of B = 18 m/s

Hence the velocity of block A is 10 m/s downwards and velocity of block B is 18 m/s upwards.

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