Physics Why two thin shirts can keep us warmer than a single thick shirt in winter ?

Air layer between two shirts behaves like insulating media
No radiation of heat takes place
Two thin shirts become thicker so prevent transmission of heat
Air layer between two shirts works as good conductor

Physics A tank filled partially with a liquid is subjected to a uniform horizontal acceleration. Which of the following is true for the surface of liquid in the tank?

The liquid surface falls down on the direction of motion and rises up on the back side of the tank
The surface of the liquid remains horizontal
The liquid surface falls down only at the center of the tank
None

Physics The wall of a dam is made thicker at the bottom than at the top because the pressure exerted by the water on the wall

Increases with depth of the wall
Depends on the area of the wall
Depends on the thickness of the wall
Increases with height of the wall

Physics Electrical burns occur principally because of

The high energy of electrons
All of these
The heat generated by the flow of electrical current through the body

Physics The function of ball bearings in a wheel is :

To convert static friction into kinetic friction
To convert kinetic friction into rolling friction
Just for convenience
To increase friction

Physics Red light is used for signals because it has

Long wavelength
High frequency
High intensity
Low refraction in the medium