Question

On the horizontal surface of a truck (μ = 0.6), a block of mass 1 kg is placed. If the truck is accelerating at the rate of 5m/sec² then frictional force on the block will be

• A. 5 N
• B. 6 N
• C. 5.88 N
• D. 8 N

Answer 1

Answer: (A)

5 N

Answer 2

Limiting friction $= \mu_{s}R = \mu_{s}mg = 0.6 \times 1 \times 9.8 = 5.88N$

When truck accelerates in forward direction at the rate of $5m/s^{2}$ a pseudo force $(ma)$ of 5N works on block in back ward direction. Here the magnitude of pseudo force is less than limiting friction So, static friction works in between the block and the surface of the truck and as we know, static friction = Applied force = 5N.