A laser light beamed at the moon takes 2.56 s to return after reflection at the moon's surface. If the angular diameter of the moon as observed from earth is = 1920, find the diameter of the moon.

The following observations were taken for determining surface tension of water by capillary tube method: Diameter of capillary, D = 1.25 10^-2 m and rise of water in capillary, h = 1.45 10^-2m

Taking g = 9.8ms^-2 and using the relation

T=(rgh/2) x 103 Nm, what is the possible error in surface tension T?

A thin copper wire of length / metre increases in length by 2% when heated through 10 C. What is the percentage increase in area when a square copper sheet of length / metre is heated through 10 C?

The least count of a stop watch is 0.2 second. The time of 20 oscillations of a pendulum is measured to be 25 seconds. The percentage error in the time period is