Astudent wanted to know what would happen in the swinger experiment if he changed the way he made the pendulum. instead of using string he used fishing line to make his pendulum the standard 38 cm long. he used a washer at the end for the pendulum bob. then he counted how many times his pendulum swung back and forth in 15 seconds. do you think he has done a good job of controlling the variables?

What does si stand for,when referring to a system of measurement

50 points to who answers this question in a clear and simple explanation : to what hight will a mass of weight of 500 n be raised in 20 seconds by a motor using 4kw of power?

Athin electrical heater is inserted between a long circular rod and a concentric tube with inner and outer radii of 20 and 40 mm. the rod (a) has a thermal conductivity of ka = 0.15 w/(m*k), while the tube (b) has a thermal conductivity of kb = 0.8 w/(m*k) and its outer surface is subjected to convection with a fluid of temperature t= -15°c and heat transfer coefficient 60 w/(m2 *k). the thermal contact resistance between the cylinder surfaces and the heater is negligible. (a) determine the electrical power per unit length of the cylinders (w/m) that is required to maintain the outer surface of cylinder b at 15°c. (b) what is the temperature at the center of cylinder a?