Heat transfer from a hot surface to a cool surface in direct contact is called
a. conduction.
b. absorption.
c. convection.
d. radiation.

An ideal otto cycle has a compression ratio of 10.5, takes in air at 90 kpa and 40°c, and is repeated 2500 times per minute. using constant specific heats at room temperature, determine the thermal efficiency of this cycle and the rate of heat input if the cycle is to produce 90 kw of power.

Explain teen pregnancy from a sociological perspective.

7.45 a student is interested in the aerodynamic drag on spheres. she conducts a series of wind tunnel tests on a 10-cm-diameter sphere. the air in the wind tunnel is at 50 â°c and 101.3 kpa. she presents the results of her tests in the form of a correlation, đť’ź = 0.0015v1.92, where đť’ź is the drag force in newtons and v is the velocity in m/s. another student realizes that the results would have been more effectively presented in terms of dimensionless parameters, say, î  1 = f (î  2) = c î  a2 , where î  1 and î  2 are dimensionless parameters and c and a are constants. what are the most appropriate dimensionless parameters (î  1 and î  2) and the corresponding values of c and a? what would be the drag on a 2-cm-diameter sphere placed in a 1-m/s, 20 â°c water stream?