The blades of a windmill sweep out a circle of area A. If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t?
Bernoulli's theorem is applicable in the case of:
In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wing are 70 m s–1and 63 m s-1 respectively. What is the lift on the wing if its area is 2.5 m2? (Take the density of air to be 1.3 kg m–3.)
The cylindrical tube of a spray pump has a cross-section of 8.0 cm2 one end of which has 40 fine holes each of diameter 1.0 mm. If the liquid flow inside the tube is 1.5 m min–1, the speed of ejection of the liquid through the holes is:
A U-shaped wire is dipped in a soap solution and removed. The thin soap film formed between the wire and the light slider supports a weight of 1.5 × 10–2 N (which includes the small weight of the slider). The length of the slider is 30 cm. The surface tension of the film is:
What is the pressure inside the drop of mercury of radius 3.00 mm at room temperature? The surface tension of mercury at that temperature () is 4.65 × 10–1 N m–1. The atmospheric pressure is 1.01 × 105 Pa.
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.
A 50 kg girl wearing high heel shoes balances on a single heel. The heel is circular with a diameter of 1.0 cm. What is the pressure exerted by the heel on the horizontal floor?
Toricelli’s barometer used mercury. Pascal duplicated it using French wine of density The height of the wine column for normal atmospheric pressure is:
(1) 11.5 m
(2) 10.5 m
(3) 9.00 m
(4) 15.0 m
A hydraulic automobile lift is designed to lift cars with a maximum mass of 3000 kg. The area of cross-section of the piston carrying the load is 425 cm2. What maximum pressure would the smaller piston have to bear?