Question

19. A horizontal force F pushes a 4 kg block (A)
which pushes against a 2 kg block (B)
shown. The blocks have an acceleration of
3m/s² to the right. There is no friction between
the blocks and the surfaces on which they slide.
What is the net force B exerts on A?
4 kg
2 kg
A
B
1) 6 N to the right 2) 12 N to the right
3) 6 N to the left 4) 12 N to the left​

Answer 1

Answer:

6N towards right

Step-by-step explanation:

If the force F applied to 4 Kg block A towards right direction.The force required to move this block will be ,

FA = mA*a

FA = 4* 3

FA=  12 N (towards right)

Against this force Body B will apply force in opposite direction towards left and the required force to move block B will be

FB=mB *a

FB = 2*3

FB=6N(towards left)

The net force will be ,

FA-FB = 12 - 6 = 6N towards right.

Answer 2

Answer:

The correct answer is option 3) 6 N to the left.

Step-by-step explanation:

Newton's third law of motion states that to every action, there is an equal and opposite reaction.

When a force exists used to the block $A$ and they move with a common acceleration $a$, then $A$ block exerts a force on block $B$.

According to Newton's third law, block B also exerts the same reaction force (R) to the $\mathrm{A}$

From $FBD$ we get, for block $B$:

$\mathrm{R}=\mathrm{M}_{\mathrm{B}} \mathrm{a}$

$=2 \times 3$

$=6 \mathrm{~N}$ to left

Therefore, the correct option is 3) 6 N to the left.

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