## A body is dropped from a tower of height 96 m. Another body is thrown up from the ground after a second with a velocity of 40 m/s.When and where they will meet?

A body is dropped from a tower of height 96 m. Another body is thrown up from the ground after a second with a velocity of 40 m/s. When and where they will meet?

SOUNDARYA asked

Answer:

For the first body,

u=0 m/s

Let S=x (from top)

x=0.5 gt^{2 } ————— (1)

For the second body,

u=40 m/s

a=-g

S=96-x

96-x=40 t -0.5 gt^{2 } ———–(2)

(1) + (2) =>

96=40t

or

t=96/40 = 2.4 s

x= 0.5 g t^{2 }=**28.224 m** from top (taking g = 9.8 m/s^{2})

## Eddy currents and applications

What ere Eddy currents and what is their application?

Rahul asked

**Answer: **

**Eddy currents** (also called **Foucault** currents) are currents induced in conductors, when the magnetic flux linked with a solid conductor changes. The change in magnetic flux can cause a circulating flow of electrons, or a current, within the body of the conductor.

The term eddy current comes from analogous currents seen in water.

**Applications**

Electromagnetic braking

Metal detectors

Eddy current adjustable-speed drives

Eddy-current testing

Electric meters (Electromechanical Induction Meters)

Eddy current brakes

Induction heating

Proximity sensor (Displacement sensors)

Traffic Detection Systems

Vending machines (detection of coins)

Coating Thickness Measurements

Sheet Resistance Measurement

Eddy current separator for metal separation

Mechanical speedometers

Safety Hazard and defect detection applications

## Chemical effects of current

How much Ag can be deposited as uniform layer on a metallic vessel using 0.2 Ampere current passed through silver salt solution for 3 hours.(1 mol of Ag=108g)

SAN THOMAS ASKED

## Matter, Antimatter and Einstein’s equation

It is my understanding that when **antimatter** comes in contact with matter that there is nothing left but pure energy.

And since energy and matter are interchangeable (E=Mc^{2}) doesn’t that mean you are actually left with all matter and no antimatter?

*Asked Ken*

**Answer**:

The equation **E = mc ^{2}** tells about

**mass – energy relation**and both matter and antimatter has a

**positive mass.**