Assume that the galaxy is 10 gyr old, the rate of star formation in the past was proportional to e^-t/t, where t is time since the galaxy formed and t = 3 gyr. and stellar lifetimes are given by t(m) = 10 gyr (m/msun)^-3. calculate the fractions of all (a) 2msun and (b) 5msun stars ever formed that are still around today.

When an object moves in uniform circular motion, the direction of its acceleration is a) in the same direction as its velocity vector. b) in the opposite direction of its velocity vector c) is directed toward the center of its circular path. d) is directed away from the center of its circular path. e) depends on the speed of the object.

In a vernier instrument the main scale is in 1/2 mm divisions .vernier is made by redividing 19 such divisions into 20 equal parts. calculate the least count of the instrument.

The transfer of heat through the movement of a gas or liquid a. convection b. conduction c. radiation