The burning rates of two different solid-fuel propellants used in aircrew escape systems are being studied. it is known that both propellants have approximately the same standard deviation of burning rate; that is, σ 1 = σ 2 = 3 cm/s. from a random sample of size n 1 = 20 and n 2 = 20 , we obtain x ¯ 1 = 18.02 cm/s and x ¯ 2 = 24.36 cm/s.

Apiston-cylinder with a volume of 0.25 m3 holds 1 kg of air (r 0.287 k/kgk) at a temperature of 100 c. heat transfer to the cylinder causes an isothermal expansion of the piston until the volume triples. how much heat is added to the piston-cylinder?

The sum of the normal stresses does not change as the stress state rotates through an angle. a)-trune b)- false

Apiping systems consists of 6 m of 6-std type k and 12 m of 4-std type k, both drawn copper tubing. the system conveys ethylene glycol at a rate of 0.013 m3/s. the pressure drop across the system is to be calculated. there are two 90° elbows in the 6-in pipe, a reduction from the 6-in pipe to the 4-in pipe and four 90° elbows in the 4-in pipe. all fittings are soldered (same as flanged) and regular. the inlet and outlet of the system are at the same height.