A wall consists of 2 layers of material: brick in front of an equal thickness of wood
If the respective thermal conductivities of the brick and wood are 1.3 J/m-s-C and 0.15 J/m-s-C, how does the temperature gradient across the wood compare to the gradient across the brick?
?Tw/?Tb = kb/kw = 1.3 / 0.15 = 8.7
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A 0.140-kg baseball is dropped from rest from a height of 2.00 m above the ground. What is the magnitude of its momentum just before it hits the ground?
A) 0.280 kg?m/s B) 0.877 kg?m/s C) 0.439 kg?m/s D) 0.620 kg?m/s E) 1.37 kg?m/s
The rotation curve for our Galaxy shows stars beyond the Sun moving more slowly than expected
Indicate whether the statement is true or false
A rocket with an initial mass of 1 000 kg adjusts its thrust by varying the rate at which mass is ejected. The ejection speed relative to the rocket is 40 km/s. If the acceleration of the rocket is to have a magnitude of 20 m/s2 at an instant when its mass is 80% of the original mass, at what rate is mass being ejected at that instant? Ignore any external forces on the rocket
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