If you toss a ball straight upward at 40 m/s with no air resistance, 6 seconds later its speed is
A) zero.
B) 10 m/s.
C) 20 m/s.
D) 30 m/s
E) 40 m/s.
Answer: C
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Arthur and Betty start walking toward each other when they are 100 m apart. Arthur has a speed of 3.0 m/s and Betty has a speed of 2.0 m/s. Their dog, Spot, starts by Arthur's side at the same time and runs back and forth between them at 5.0 m/s
By the time Arthur and Betty meet, what distance has Spot run?
Shapley found the distance to the center of the galaxy by studying the distance to open clusters
a. True b. False Indicate whether the statement is true or false
Water enters a double pipe heat-exchanger at 60°C. The water flows on the inside through a copper tube 2.54 cm ID at a velocity of 2 cm/s. Steam flows in the annulus and condenses on the outside of the copper tube at a temperature of 80°C. Calculate the outlet temperature of the water if the heat exchanger is 3-m-long.
GIVEN
• Water flow through a tube in a double pipe heat-exchanger
• Water entrance temperature (Tb,in.) = 60°C
• Inside tube diameter (D) = 2.54 cm = 0.0254 m
• Water velocity (V) = 2 cm/s = 0.02 m/s
• Steam condenses at (Ts) = 0.80°C on the outside of the pipe
• Length of heat exchanger (L) = 3 m
FIND
• Outlet temperature of the water (Tb,out)
ASSUMPTIONS
• Steady state
• Thermal resistance of the copper pipe is negligible
• Pressure in the annulus is uniform therefore, Ts is uniform
• Heat transfer coefficient of the condensing steam is large (see Table 1.4) so its thermal resistance can be neglected
• Outside surface of the heat exchanger is insulated
SKETCH
Extremely high-density matter in which, due to quantum mechanical effects, pressure does not depend on temperature is termed__________
A) culminated matter B) fusional matter C) degenerate matter D) retrograde matter