* SI unit of Impulse is Newton Second(Ns). 

* Impulse is basically change in momentum and the dimensionally equivalent unit of momentum is the kilogram meter per second (kg⋅m/s)

Moment arm is the perpendicular distance between point of application of force and axis of rotation.

The longer the moment arm is the more load will be applied to the joint axis through leverage.

The maximum velocity up to which fluid motion is streamline is called critical velocity. Clearly, if the velocity of flow is below critical velocity, flow is streamlineand of the velocity above the critical velocity, flow is turbulent.

* When a liquid has concave meniscus, the angle of contact is acute. When it has a convex meniscus, the angle of contact is obtuse. 

* The cohesive forces between the molecules of mercury is more than the adhesive forces between them and glass. Thus convex meniscus is formed. The angle made by the mercury from the glass surface is always obtuse. 

* The adhesive forces between the molecules of glass and water is more than the cohesive forces between the molecules of water. Thus concave meniscus is formed. The angle made by the water from the glass surface is always acute.

• Instrument for measuring thickness or amount of rainfall is called is Hyetometer. The first records of rainfall was kept by greeks in the year 500 B.C.
• Hygrometer is used for measuring the the water vapor in the atmosphere.
• Lucimeter is used to measure intensity of light.

an electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. Because the wavelength of an electron can be up to 100, 000 times shorter than that of visible light photons, the electron microscope has a higher resolving power than a light microscope and can reveal the structure of smaller objects.

Projectile motion is a type of motion in which an object is moves along a curved path under the action of gravity. A projectile launched on level ground with an initial speed V₀ at an angle θ above the horizontal will have the 

• Same range as a projectile launched with an initial speed Vo at 90 ° − θ. 

• Maximum range when θ = 45 °.

A Galvanometer van be converted into an ammeter by connecting a low resistance in parallel. A galvanometer can be converted in to a voltmeter by connecting a high resistance in series.

This is because the scattering in red lights is less than that of yellow colour. The longest visible wavelength is red and the shortest isviolet. 

A moving coil galvanometer can be used as a voltmeter by inserting a resistorinseries with the instrument. The galvanometer has a coil of fine wire suspended in a strong magnetic field.