Which one of the following is true from the given statements?
1. | Surface tension of liquids generally increases with temperatures. |
2. | Viscosity of gases decreases with temperature. |
3. | For solids with an elastic modulus of rigidity, the shearing force is proportional to the shear strain. |
4. | For the model of a plane in a wind tunnel, turbulence occurs at a smaller speed than turbulence for an actual plane. |