Question Library

Efficiency = (MA)/V.R x 100% = (load)/Effort x (1)/V.R = (800)/400 x (1)/6 x 100% = 33.3%

A bod y is said to be in stable equilibrium if after a slight displacement, the body returns to its former position. Thus, position III, VI and XI represents position of stable equilibrium

V = f\lambda f = (v)/\lambda = (420)/42 = 10 HZ Period, T = (1)/F = (1)/10 = 0.1 secs

Length of the string L = y + x = 0.5m ∴ x = L - y = distance moved in the direction of force (which is the weight) when the body is released But cos 60o = y/0.5 ∴ y = 0.5cos60 = 0.5 x 1/2 = 0.25 ∴ x = l - y = 0.5 - 0.25 = 0.25m Work done = force x distance moved in the direction of force. = 0.1 x 0.25 = 0.025J

Since relative density = mass of substance mass of equal volume of water relative density bottle should be used to determine the mass of the substance, and mass of an equal volume of water by filling the bottle with the powder and water respectively and weighed with the beam balance.

The instrument used in measuring relative density is hydrometer

Density (D) = \(\frac{mass}{volume}\) \(\therefore Mass = Density \times volume\) = \(0.4 \times 20 = 8kg\) The initial volume = \(\frac{Mass}{\text{Initial density}}\) = \(\frac{8}{0.8} = 10m^{3}\)

Energy stored in a stretched wire (strain energy) = average force x extension = (1)/2 Fe = (1)/2 x 300 N (30.5 - 30.0) x 10-2 m = (300)/2 x 0.5 x 10-2 = 0.75J

Thrust = pressure x area = 100 pa x 3 m2 = 300 N

The low freezing point of alcohol, -115^\circc enable low temperatures to be measured. mercury freezes at 39^\circc, and cannot be used in countries like Russia where winter temperatures of -40^\circc are common

Infrared rays falling on the skin causes the skin causes the sensation of warmth. since the objects are hot, the correct option is informed.

T = 27 + 273 = 300 K, volume, V = 10-2 m3 molar gass constant, R = 8.3 Jmol- 1k - 1 number of mole, n = 1 PV = NRT i.e P = (NRT)/V = (1 x 8.3 x 300)/10-2 = 2.49 x 10\(^5\) Nm\(^-2\)

Metals P, Q original length lP, lQ Increase in length \DeltalP, \DeltalQ Linear expansivities \alphaP, \alphaQ ∴ \alphaP/\alphaQ = 2/3 ; and lP/lQ = 3/4 But increase in length, \Deltal = \alphal\Delta\theta ∴\DeltalP = \alphaPlP\Delta\theta \DeltalQ = \alphaQlQ\Delta\theta ∴ \DeltalP = \alphaPlP\Delta\theta = 2 x 3 = 1 \DeltalQ \alphaQlQ\Delta\theta 3 4 2 ∴ Ratio of increase in length of P to Q = 1:2

A saturated vapour is one which is in dynamic equilibrium with its own liquid; that is as many go from the liquid to the vapour state every second return back to liquid.

The acceleration of free fall due to gravity is independent of mass of the body. Therefore, ignoring air resistance, which affects feather more than the stone, the stone and the feather will both reach the ground at the same time