Question

For the system shown in figure, pulley and string are ideal. Value of force F so that acceleration of 3 kg is 5 m/s2 in the upward direction. [g = 10 m/s2)​

Answer 1

Answer:

B AND C

Explanation:

Correct option is

B

2 kg

C

18 kg

Friction force by block of mass 20 kg, f=μ(20)(10)=0.4×200=80 N

In equilibrium,

for minimum value of m, mg=10g−80=20,m  

min

​

=2kg

for max of m, mg=10g+80=180,m  

max

​

=18kg

So (B) , (C) are the correct option.

Answer 2

Answer:

Force is applied on the 2nd rope is 2mg so the tension developed is 2mg.

So, the net tension on 1st rope will be 2T that is 2×mg=4mg

4mg−mg=ma

a=3g