CBSE
Multiple Choice QuestionsSixty four spherical rain drops of equal size are falling vertically through air with a terminal velocity 1.5 ms-1 . If these drops coalesce to form a big spherical drop, then terminal velocity of big drop is
8 ms-1
16 ms-1
24 ms-1
32 ms-1
A liquid flows through a pipe of non-uniform cross-section. If A1 and A2 are the cross-sectional areas of the pipe at two points, the ratio of velocities of the liquid at these points will be
A1A2
A beaker of radius 15 cm is filled with a liquid of surface tension 0.75 N/m. Force across an imaginary diameter on the surface of the liquid is
0.075 N
1.5 × 10-2 N
0.225 N
2.25 × 10-2 N
A cylinder of height 20 m is completely filled with water. The velocity of efflux of water (in ms-1 ) through a hole on the side wall of the cylinder near its bottom, is
10
20
25.5
5
A metal plate of area 103 cm2 rests on a layer of oil 6 mm thick. A tangential force of 10-2 N is applied on it to move it with a constant velocity of 6 cms-1. The coefficient of viscosity of the liquid is
0.1 poise
0.5 poise
0.7 poise
0.9 poise
A square wire frame of size L is dipped in a liquid. On taking out a membrane is formed. If the surface tension of liquid is T, then force acting on a frame will be
2T L
4T L
8T L
16T L
A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be
4 cm
8 cm
10 cm
20 cm
A manometer connected to a closed tap reads 4.5 x 105 Pa. When the tap is opened the reading of the manometer falls to 4 x 105 Pa. Then the velocity of flow of water is
7 ms-1
8 ms-1
9 ms-1
10 ms-1
Radius of an air bubble at the bottom of the lake is r and it becomes 2 r when the air bubble rises to the top surface of the lake. If P cm of water be the atmospheric pressure, then the depth ofthe lake is
2 P
8 P
4 P
7 P
A piece of ice is floating in a jar containing water. When the ice melts, then the level of water
rises
falls
remains unchanged
rises or falls
