1.

Two blocks A and B of same masses attatched with a light spring are suspended by a string as shown in figure .Find the acceleration of block A and block B just after cut the string .​

Answer»

Answer :-

\implies \boxed{ \sf{a_{A} = 2g \: or \: 20 \:  \frac{m} {{s}^{2} } }} \\   \implies \boxed{ \sf{ a_{B}  = 0}} \:

To Find :-

→ Acceleration of block "A" and "B" .

Explanation:-

According to the question -

→ Mass of both blocks is same .

(1) Before cut the string ( refer to attachment )

Before cut the string TENSION (T) , spring force (kx) and gravitational force (mg) is working on block "A" ,

Before cut the string there is no acceleration in both blocks .

hence ,

→ T - kx - mg = 0 .....eq.(1) ( on block A)

and ,

→ kx - mg = 0 ( on block B)

→ kx = mg [ put in eq.(1) ]

→ T - mg - mg = 0

→ T = 2mg

now,

(2) Just after cut the string ( refer to the attachment )

After cutting the string these is Acceleration in both block .( After cut the string Tension is REMOVED on block "A" )

hence ,

\sf{ Let \:acceleration\:of\:block\:A\:is\:a_{A}}\\  \sf{and\:of\:B\:is\:a_{B}}

• On block "B"

\implies \sf{ kx - mg = ma_{B} } \\  \\  \implies \sf{mg - mg =m a_{B} } \\   \\  \implies \boxed{ \sf{ a_{B}  = 0}}

• On block "A"

\implies \sf{ mg + kx = ma_{A}} \\  \\  \implies \sf{ma_{A} = 2mg} \\  \\  \implies \boxed{ \sf{a_{A} = 2g \: or \: 20 \:  \frac{m} {{s}^{2} } }}

Note - After cut the string these is no normal CONTACT force .( so NEGLECT it )



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