Question

29. Slab A is resting on a frictionless floor. Its mass is
35 kg. Block B of mass 7 kg is resting on it as shown
in the diagram. The co-efficient of static friction
between the block and slab is 0.5. While kinetic
friction is 0.4, Force F is applied to the block B.
(g=10ms-2)
B m2
>F
А.
mi
The minimum value of force F to cause block B to
move with respect to slab A is :-​

Answer 1

Static friction friction force between two blocks

f

s

≤μN

N=mg=7×10=70N

f

s

≤μ

s

×70

f

s

≤0.5×70

f

s

≤35N

here force applied is grater than static friction

hence body is in motion, then there is kinetic friction

f

k

=μ

k

×70

f

k

=0.4×70

f

k

=28N

for mass 35 kg force applied is only kinetic friction

f

1

=f

k

=28N

acceleration of mass 35 kg is

a=

35

f

1

=

35

28

=0.8m/s

2

Answer 2

Answer:

above answer is wrong correct answer is option 2