Which of the following wires would have the greatest resistance? O a copper wire 20 cm in length at 60°C
O a copper wire 20 cm in length at 40°C
O a copper wire 40 cm in length at 40°C
O a copper wire 40 cm in length at 60°C

An important dimensionless parameter concerned with very high-speed flow is the mach number, defined as v/c, where v is the speed of the object such as an airplane or projectile, and c is the speed of sound in the fluid surrounding the object. for a projectile traveling at 1170 mph through air at 50 ˚f and standard atmospheric pressure, what is the value of the mach number?

Atank has a shape of a cone with a radius at the top of 2 m and a height of 5 m. the tank also has a 1 m spout at the top of the tank. the tank is filled with water up to a height of 2 m. find the work needed to pump all the water out the top of the spout. (use 9.8 m/s2 for g and the fact that the density of water is 1000 kg/m3.)

Scientific models are based on current knowledge, which can limit their effectiveness when new discoveries are made.