The distance of a galaxy is of the order of `10^25` m. Calculate the order of magnitude of time taken by light to reach us from the galaxy.

What is the order of magnitude of light year in etre?

What is the order of magnitude of the following Velocity of light.

Two equal charges placed in air and separated by a distance of 2 m repel each other with a force of 10^-4 N. Calculate the magnitude of either of the charges.

Time taken by light to cross nuclear diameter is of the order of

Two fixed, equal, positive charges, each of magnitude 5xx10^-5 coul are located at points A and B separated by a distance of 6m. An equal and opposite charge moves towards them along the line COD, the perpendicular bisector of the line AB. The moving charge, when it reaches the point C at a distance of 4m from O, has a kinetic energy of 4 joules. Calculate the distance of the farthest point D which the negative charge will reach before returning towards C.

An athlete completes 100m race on a straight track. Calculate the distance and magnitude of displacement of athlete during the race.

A first order reaction is 20% complete in 10 minutes. Calculate the time taken for the reaction to go to 75% complete.