Question

I there is a block of mass 10kg and a force of 5n is acting on it I the positive x direction and a force of 3n I the negative x direction as shown in the figure then calculate it's acceleration​

Answer 1

For 10kg block, f is frictional force
f
1max
​
=μ
1
​
μ
2
​
=μ
1
​
(10g)=0.1(10×10)=10N

i) if F=2N then acting friction
f
1
​
=F=2N
(A) is correct.
for 5 kg block;
f
2max
​
=μ(10+5)g=0.3×15×10=45N


ii) if F=30N then;

F−F
1max
​
=10a

10a=30−10=20

a=2m/s
2


(B) is correct.

iii) if μ
1
​
changed to 0.5;

then f
1max
​
=μ
1
​
(10g)=0.5×10×10=50N

In the case acting friction will be F
2max
​


Since,
F
1max
​
=F
2max
​


Block 10kg and 5kg both move together then F
min
​
to begin is

F
min
​
−F
max
​
=0

F
min
​
=F
2max
​
=45N

(c) is correct.

iv) if μ=0.1 , then f
max
​
=10N and,

f
2max
​
=45N

f
2max
​
>f
1max
​
always for any any value of N. Hence, 5kg block never move on the ground.

So, option (A), (B), (C), and (D) are correct.


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