In the given figure the blocks A, B and C weigh 4 kg, 6 kg and 8 kg respectively. The co-efficient of sliding friction between any two surfaces is 0.5. The force $\overrightarrow{\mathrm{F}}$ required to slide the block C with constant speed is ______ N. (Used $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}$)

JEE Main · 2026 · 24 Jan 2026 · Shift 1 · Laws of Motion

In the given figure the blocks A, B and C weigh 4 kg, 6 kg and 8 kg respectively. The co-efficient of sliding friction between any two surfaces is 0.5. The force

F

required to slide the block C with constant speed is ______ N. (Used

g = 10 m / s^{2}

)

Answer: 190

Solution

Sliding block

C

at constant speed means the applied force balances every kinetic-friction force set up by the stack. The ground supports all three blocks, so friction under

C

μ (m_{A} + m_{B} + m_{C}) g = 0.5 \times 18 \times 10 = 90 N

. Blocks

A

and

B

rest on

C

, so the friction at the

B

–

C

surface is

μ (m_{A} + m_{B}) g = 0.5 \times 10 \times 10 = 50 N

. The string from

B

passing over the wall pulley holds

B

stationary and adds its tension of

50 N

to the load on

C

. Adding the three contributions,

F = 90 + 50 + 50 = 190 N

JEE Main · 2026 · 24 Jan 2026 · Shift 1 · Integer answer

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JEE Main · 2026 · 24 Jan 2026 · Shift 1 · Laws of Motion

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