Physics

From water at 0°C to water at 4°C, on addition of heat, the water surprisingly, contracts till it reaches maximum density at 4°C. This negative thermal expansion is termed as the anomalous expansion of water._x000D_ From water at 4°C to water at 100°C, water shows a positive cubical thermal expansion like other substances and gradually expand with the increase in temperature.

Radar, which stands for radio detection and ranging, is a system that uses reflected radio waves to detect objects and measure their distance and speed. For example, police use radar to calculate the speed of cars.

Angular momentum has the same dimensions as that of Planck’s constant.

Magnetism is caused by the motion of electric charges.

A boy is swinging a ball attached to a string in a horizontal circle. If the string snaps it will continue to travel along a tangent to the circle at the point the ball was at the time of snapping and finally fall down.

Hot water is poured simultaneously in four metallic tumblers painted outside with different paints. After some time the water will be found to have cooled most in the tumbler painted rough black. Black surfaces are good emitters of heat.