A liquid is contained in a vertical tube of semicircular cross-section (figure). The contact angle is zero. The forces of surface tension on the curved part and on the flat part are in ratio:
1. \(1:1\)
2. \(1:2\)
3. \(\pi:2\)
4. \(2: \pi\)
When a capillary tube is dipped into a liquid, the liquid neither rises nor falls in the capillary.
a. | the surface tension of the liquid must be zero. |
b. | the contact angle must be \(90^\circ.\) |
c. | the surface tension may be zero. |
d. | the contact angle may be \(90^\circ.\) |
Choose the correct option:
1. | (a) and (b) |
2. | (b) and (c) |
3. | (c) and (d) |
4. | all of these |
Water is flowing through a long horizontal tube. Let \(P_A\) and \(P_B\) be the pressures at two points \(A\) and \(B\) of the tube.
1. | \(P_A\) must be equal to \(P_B\). |
2. | \(P_A\) must be greater than \(P_B\). |
3. | \(P_A\) must be smaller than \(P_B\). |
4. | \(P_A\) = \(P_B\) only if the cross-sectional area at A and B are equal. |
Water enters through end \(A\) with a speed \(v_1\) and leaves through end \(B\) with a speed \(v_2\) of a cylindrical tube AB. The tube is always completely filled with water. In case I the tube is horizontal, in case II it is vertical with the end \(A\) upward and in case III it is vertical with the end \(B\) upward. We have \(v_1=v_2\) for:
1. case I
2. case II
3. case III
4. each one
Equal mass of three liquids are kept in three identical cylindrical vessels \(A\), \(B\) and \(C\). The densities are \(\rho_A,~\rho_B,~\rho_C\) with \(\rho_A<\rho_B<\rho_C\) . The force on the base will be:
1. | \(A\) | maximum in vessel
2. | \(B\) | maximum in vessel
3. | \(C\) | maximum in vessel
4. | equal in all the vessels |
1. | 2. | ||
3. | 4. |
1. | \(1\) hr | 2. | \(\sqrt2\) hr |
3. | \(2\) hr | 4. | \(4\) hr |
1. | decreases |
2. | increases |
3. | remains unchanged |
4. | first increases and then decreases |