Question

23. A block of mass 2 kg is kept on horizontal surface
with coefficient of friction as indicated in figure. A
horizontal time varying force F = (2 + t)N starts
acting on the block at t = 0. Find the time after
which the block begins to slide (g = 10 ms?)
2 kg
→ F= (2 + 1)N
H, = 0,6
H. = 0.5
(1) 2 s
(2) 85
(3) 10 s
(4) 16 S
​

Answer 1

Answer:

B . 8s

Explanation:

The acceleration will be zero upto time,t before when static friction is acting.

the time variable force reaches value of maximum static friction force,

F=f max  = μ s N⇒2t=0.8×2×10

                               ⇒t=8s

the block will start sliding just after this time with acceleration equal to:

F−f  max =ma⇒2t−0.8×2×10=2a

a=  2t−0.8×2×10 /2

=t−8