In a museum exhibit of a simple pendulum, a very small but dense 6.0-kg ball swings from a very light 2.5-m wire
The ball is released from rest when the pendulum wire makes a 65° angle with the vertical, and it swings in a circular arc with no appreciable friction or air resistance. What is the tension in the wire just as the ball swings through its lowest position? A) 11 N
B) 59 N
C) 68 N
D) 130 N
E) 0 N
D
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Projectile Motion: A marble moving 1.48 m/s rolls off the top edge of a 125-cm high table in a room where there is no appreciable air resistance and the acceleration due to gravity is 9.80 m/s2.(a) How far from the base of the table will it strike the floor?(b) How long will it be in the air?
What will be an ideal response?
A gas-fired industrial furnace is used to generate steam. The furnace is a 3 m cubic structure and the interior surfaces are completely covered with boiler tubes transporting pressurized wet steam at 150°C. It is desired to keep the furnace losses to 1% of the total heat input of 1 MW. The outside of the furnace can be insulated with a blanket-type mineral wool insulation [k = 0.13 W/(m °C)], which is protected by a polished metal sheet outer shell. Assume the floor of the furnace is insulated. What is the temperature of the metal shell sides? What thickness of insulation is required?
GIVEN
? An insulated cubic furnace with steam filled tubes on the inner walls
? Steam temperature (Tst) = 150°C
? Length of a side of the furnace (L) = 3 m
? Thermal conductivity of mineral wool insulation (ki) = 0.13 W/(m°C)
? Insulation is protected by metal sheet outer shell
? Furnace losses (qc) = 1% of total heat input
? Total heat input (qin) = 1 MW = 106 W
FIND
(a) Temperature of the metal sheel sides (Ts)
(b) The thickness of insulation (s) required
ASSUMPTIONS
? Steady state operation
? Thermal resistance of the convection within the steam pipes, the steam pipe walls, the furnace
walls, and the metal shell negligible compared to that of the insulation
? Air outside the furnace is still
? The floor is well insulated —heat loss is negligible
? Temperature of the metal shell is uniform
? Ambient temperature (T?) = 20°C (293 K)
? Edge effects are negligible
? The emissivity of the polished metal shell (E) = 0.05 (see Table 9.2)
SKETCH
PROPERTIES AND CONSTANTS
From Appendix 1, Table 5, the Stephan-Boltzmann Constant
The density of a neutron star is comparable to the density of an atomic nucleus
Indicate whether the statement is true or false
Suppose the circuit parameters in a series RLC circuit are: L = 1.00 ?H, C = 10.0 nF, R = 100 ?, and the source voltage is 220 V. Determine the resonant frequency of the circuit and the amplitude of the current at resonance.
What will be an ideal response?