A room measuring 21 m by 18 m and 13 m high has to be lighted by four lighting fixtures suspended 3 m from ceiling. The ceiling points are symmetrically placed on the two diagonals so that each point is 7 m from the center of the ceiling. An illumination of 12 lux apart from any effect due to the walls and ceiling is required on the center of a table 3 m high placed at the center of the room. What luminous intensity must each unit give in direction necessary to produce this result?

Ascientist is tracking an object orbiting the sun that is found between mars and jupiter. in order to classify the object as an asteroid, it must be at least

1. consider the case in which air fills air shocks on a truck trailer. the pressure in the shocks is 2 mpa. the temperature is 300 k. the diameter of the shock piston is 10 cm and the initial length of the cylindrical cavity containing the compressed air is 40 cm. a. the truck is gradually loaded over a period of a day in a static setting. the temperature is held constant for the atmosphere and thus for the gas shock. calculate the compressibility of the air in the shock for this condition when the truck is initially being loaded. b. if the shocks were loaded in a dynamic setting by driving over bumps, what would be the compressibility? state your assumption. c. what is the initial load on the shock if the shock is in an atmospheric 100 kpa? d. if the shock is compressed using the process described in part a, and the air shock compressed air cavity length decreases to 20 cm, what is the additional load applied to the shock?

As a car drives with its tires rolling freely without any slippage, the type of friction acting between the tires and the road is 100) a) static friction. b) kinetic friction. c) a combination of static and kinetic friction. d) neither static nor kinetic friction, but some other type of friction. e) it is impossible to tell what type of friction acts in this situation.