Oral work :
Name the device installed on the top of the buildings to pretect it from a lightning strike.

Oral work : Name some natural phenomena.

Oral work : Name a device used for measuring time in olden times .

Oral work : Which device is used to detect the electric charge on an object?

Oral work : Name the leguminous crops cultivated to restore the fertility of soil .

A 1.5 m tall boy is standing at some distance from a 30 m tall building. The angle of elevation from his syes to the top of the building increases from his eyes to the top of the building increases from 30^@ to 60^@ as he walks towards the building. Find the distance he walked towards the building.

Give scientific reasons: If a feather and a stone are released from the top of a building simultaneously, the stone reaches the ground earlier than the feather.

A boy drops a coin form the top of a building with is 49m high. Find the velocity with which the coin strikes. Calculate total time (t) it takes to return to the surface of earth .

Answer the following questions : Name two devices whose working is based on the phenomenon of persistance of vision .

Solve the following examples / numerical problems: A body is released from the top of a building of height 19.6 m . Find the velocity with which the body hits the ground.