Two blocks of masses 7 kg and 5 kg are placed in contact with each other on a smooth surface….

Q: Two blocks of masses 7 kg and 5 kg are placed in contact with each other on a smooth surface. If a force of 6 N is applied on the heavier mass, the force on the lighter mass is

Numerical

(a) 3.5 N

(b) 2.5 N

(c) 7 N

(d) 5 N

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Ans: (b)
Sol: Let R be the force applied on lighter block (5 kg) towards right , hence on 7 kg block it will be towards left .

For 7 kg block ,

6 – R = 7 a …(i)

For 5 kg block ,

R = 5 a ….(ii)

On solving (i) & (ii)

a = 0.5 m/s^2 ,

R = 5 × 0.5 = 2.5 N