(a) Calculate the rate of heat conduction through house walls that are 13.0 cm thick and that have an average thermal conductivity twice that of glass wool. Assume there are no windows or doors. The surface area of the walls is 12 0 m 2 and their inside surface is at 18 .0 ° C , while their outside surface is at 5 .00 ° C . (b) How many 1-kW room heaters would be needed to balance the heat transfer due to conduction?
(a) Calculate the rate of heat conduction through house walls that are 13.0 cm thick and that have an average thermal conductivity twice that of glass wool. Assume there are no windows or doors. The surface area of the walls is 12 0 m 2 and their inside surface is at 18 .0 ° C , while their outside surface is at 5 .00 ° C . (b) How many 1-kW room heaters would be needed to balance the heat transfer due to conduction?
(a) Calculate the rate of heat conduction through house walls that are 13.0 cm thick and that have an average thermal conductivity twice that of glass wool. Assume there are no windows or doors. The surface area of the walls is
12
0
m
2
and their inside surface is at
18
.0
°
C
, while their outside surface is at
5
.00
°
C
. (b) How many 1-kW room heaters would be needed to balance the heat transfer due to conduction?
A spring is attached to an inclined plane as shown in the figure. A block of mass m = 2.71 kg is placed on the incline at a distance d = 0.285 m along the incline from the end of the spring. The block is given a quick shove and moves down the incline with an initial speed v = 0.750 m/s. The
incline angle is = 20.0°, the spring constant is k = 505 N/m, and we can assume the surface is frictionless. By what distance (in m) is the spring compressed when the block momentarily comes to rest?
m
m
0
k
wwww
A block of mass m = 2.50 kg situated on an incline at an angle of
k=100 N/m
www
50.0° is connected to a spring of negligible mass having a spring constant of 100 N/m (Fig. P8.54). The pulley and incline are frictionless. The block is released from rest with the spring initially unstretched.
Ө
m
i
(a) How far does it move down the frictionless incline before coming to rest?
m
(b) What is its acceleration at its lowest point?
Magnitude
m/s²
Direction
O up the incline
down the incline
(a) A 15.0 kg block is released from rest at point A in the figure below. The track is frictionless except for the portion between points B and C, which has a length of 6.00 m. The block travels down the track, hits a spring of force constant 2,100 N/m, and compresses the spring 0.250 m
from its equilibrium position before coming to rest momentarily. Determine the coefficient of kinetic friction between the block and the rough surface between points B and C.
-A
3.00 m
B
C
-6.00 m
i
(b) What If? The spring now expands, forcing the block back to the left. Does the block reach point B?
Yes
No
If the block does reach point B, how far up the curved portion of the track does it reach, and if it does not, how far short of point B does the block come to a stop? (Enter your answer in m.)
m
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
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