Question

Two persons just manage to push a block from left to right direction along a horizontal level road with uniform velocity. When the same block is pushed by three persons in same direction a constant acceleration of 0.2 ms–2 is produced in the block. If the five persons push the block in same direction together, then the magnitude of acceleration of the block will be [Assume that each person applies the force equal in magnitude]
(1) 0.4 ms–2
(2) 0.6 ms–2
(3) 0.8 ms–2
(4) 1 ms–2

Answer 1

$\bold{Hello}$



Concept : Forces and Friction


★ Case-1) When 2 person pushes the block .


Let the force be F applied by each . So when 2 will apply , force will be 2F

now , according to the question , when 2 person manage to push a block , the block moves with $\bold{Constant \:\:Velocity}$


This means , that the force applied by the 2 person is equal to the force applied in opposite direction ( Frictional force )


Let frictional force be Fr



Equation :- 2F = Fr



★ Case-2) In this case acceleration is produced.

Three person applies force ( 3F ) and frictional force will be same i.e Fr

Equation. :- 3F - Fr = 0.2m ( m is the mass of block which is unknown )


Let us put the value of Fr which we know.


=> 3F - 2F = 0.2 m

=> F = 0.2 m .......... *





Case-3) When the block is pushed by 5 people ( 5F )


Equation :- 5F - Fr = ma

again putting value of Fr .

=> 5F - 2F = ma

=> 3F = ma .........*


put the value F in the above equation . that is F = 0.2m


=> 3 ( 0.2 m ) = ma

=> 0.6 m = ma



=> $\boxed{\bold{\underline{a = 0.6 m/s^{2}}}}$









Hope It Helps You. ^_^ :-)

Answer 2

Hey !

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Two persons just manage to push a block from left to right direction along a horizontal level road with uniform velocity. When the same block is pushed by three persons in same direction a constant acceleration of 0.2 ms–2 is produced in the block. If the five persons push the block in same direction together, then the magnitude of acceleration of the block will be [Assume that each person applies the force equal in magnitude]

(1) 0.4 ms–2

(2) 0.6 ms–2

(3) 0.8 ms–2

(4) 1 ms–2

______________________________

Thanks !