Question Details

A horizontal force 10 N is applied to a block A as shown in figure. The mass of blocks A and B are 2 kg and 3 kg, respectively. The blocks slide over a frictionless surface. The force exerted by block A on block B is :

Options

A

zero

B

4N

C

6N

D

10N

Show Answer

Correct Answer :

Option C

6N

6N

Solution :

**Correct answer:** 6 N

The diagram (see the provided image) shows two blocks, A (2 kg) and B (3 kg), placed side‑by‑side on a frictionless horizontal surface. A horizontal force of 10 N is applied to block A, pushing both blocks together.

Since the surface is frictionless, the only external horizontal force on the system is the 10 N applied to block A. The two blocks move as a single system with a common acceleration .

Using Newton’s second law for the whole system:

a = \frac{F_{\text{ext}}}{m_{\text{total}}}

where Fext = 10 N and mtotal = mA + mB = 2 kg + 3 kg = 5 kg.

Calculate the acceleration:

a = \frac{10\ \text{N}}{5\ \text{kg}} = 2\ \text{m/s}^2

Now consider block B alone. The only horizontal force acting on block B is the contact force exerted by block A, which we denote as FAB. Applying Newton’s second law to block B:

F_{AB} = m_{B}\, a

Substituting mB = 3 kg and a = 2 m/s²:

F_{AB} = 3\ \text{kg} \times 2\ \text{m/s}^2 = 6\ \text{N}

Therefore, the force that block A exerts on block B is **6 N**.

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