A cube with a mass =20g wettable water floats on the surface of water. Each face of the cube is α=3cm long. Surface tension of water is 70dyn/cm. The distance of the lower face of the cube from the surface of water is (g=980cm/s2).
A
2.3cm
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
4.6cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
9.7cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
12.7cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is A2.3cm Since the angle of contact for cube and water is 0o, Surface tension provides a downward force to the cube. And for the equilibrium of the cube. Downward force=upward force⇒weight + surface tension force=buoyant force⇒mg+4αT=lα2ρgHere l=distance of the lower face of the cube from the surface of water⇒l=mg+4αTα2ρg⇒l=20×980+4×3×7032×1×980⇒l=2.3175cm≈2.3cm