Why are some appliances called vampires

Alow cost, low earth orbit (leo) satellite is to be fabricated at a university, for subsequent launch by rocket. what are the constraints and objectives for selection of a material suitable for the satellite bus (i.e. the structure)? explain each in brief. (15 marks) b)suggest sources of data which could support the selection of materials for applications in space. (5 marks) c) set weights for the objectives listed in (2a) using the digital logic method. (5 marks)

A23 kg log of wood begins from rest, 300 m up a sluice (a water track used to transport logs, think of it as an inclined plane with negligible friction) inclined at 20° to the horizontal. after it reaches the flat waterway at the bottom it collides elastically with a 100 kg block of wood initially at rest near the base of the incline. (a) how long does it take the 23 kg log to travel down the incline? (b) what is the speed of the 23 kg log at the bottom of the incline? (c) what are the velocities of both blocks of wood after the collision? (d) what is the total kinetic energy before the collision? (e) what is the kinetic energy of the 23 kg log after the collision? (f) what is the kinetic energy of the 100 kg block of wood after the collision? (g) what is the total kinetic energy after the collision? (h) compare the total initial and total final kinetic energies. is this consistent with what you would expect for elastic collisions? explain!

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?