A mains operated motor raises an 8500, N,8500N weight to a height of 2, point, 7, m,2.7m. The electrical work done by the mains supply is 29000, J,29000J. Calculate the efficiency of this process.

Suppose that a comet that was seen in 563 a. d. by chinese astronomers was spotted again in year 1951. assume the time between observations is the period of the comet and take its eccentricity as 0.986. what are (a) the semimajor axis of the comet's orbit and (b) its greatest distance from the sun?

There are two-speed cameras, one in an are where the speed limit is 30 km/h and another where the speed limit is 50 km/h. in which will there be a smaller time interval between the photographs? explain your answer.

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.