You have designed a machine that requires 1000 J of work from a motor for every 800 J of useful work done by the machine. What is the efficiency of the machine?

Which statement is true for light passing into a medium that is more optically dense than the first medium through which it past

15. give an example for some particles or waves that are moving faster than light in everyday life 16. what is a laser? 17. what is an oscilloscope? 18. what does it means practically that nothing is faster than light in vacuum? 19. what is vacuum?

Awater-filled u-tube manometer is used to measure the pressure inside a tank that contains air. the water level in the u-tube on the side that connects to the tank is 5 ft above the base of the tank. the water level in the other side of the u-tube (which is open to the atmosphere) is 2 ft above the base. determine the pressure within the tank.