A thermos for liquid helium. A physicist uses a cylindrical metal can 0.250 m high and 0.090 m in diameter to store liquid helium at 4.22 K; at that temperature the heat of vaporization of helium is 2.09 × 10 4 J/kg. Completely surrounding the metal can are walls maintained at the temperature of liquid nitrogen, 77.3 K, with vacuum between the can and the surrounding walls. How much helium is lost per hour? The emissivity of the metal can is 0.200. The only heat transfer between the metal can and the surrounding walls is by radiation .
A thermos for liquid helium. A physicist uses a cylindrical metal can 0.250 m high and 0.090 m in diameter to store liquid helium at 4.22 K; at that temperature the heat of vaporization of helium is 2.09 × 10 4 J/kg. Completely surrounding the metal can are walls maintained at the temperature of liquid nitrogen, 77.3 K, with vacuum between the can and the surrounding walls. How much helium is lost per hour? The emissivity of the metal can is 0.200. The only heat transfer between the metal can and the surrounding walls is by radiation .
A thermos for liquid helium. A physicist uses a cylindrical metal can 0.250 m high and 0.090 m in diameter to store liquid helium at 4.22 K; at that temperature the heat of vaporization of helium is 2.09 × 104 J/kg. Completely surrounding the metal can are walls maintained at the temperature of liquid nitrogen, 77.3 K, with vacuum between the can and the surrounding walls. How much helium is lost per hour? The emissivity of the metal can is 0.200. The only heat transfer between the metal can and the surrounding walls is by radiation.
2
C01: Physical Quantities, Units and Measurementscobris alinu zotinUD TRO
Bendemeer Secondary School
Secondary Three Express Physics
Chpt 1: Physical Quantities, Unit and Measurements Assignment
Name: Chen ShiMan
loov neowled soria
25
( 03 ) Class: 3 Respect 6 Date: 2025.01.22
1
Which group consists only of scalar quantities?
ABCD
A
acceleration, moment and energy store
distance, temperature and time
length, velocity and current
mass, force and speed
B
D.
B
Which diagram represents the resultant vector of P and Q? lehtele
시
bas siqpeq olarist of beau eldeo qirie-of-qi
P
A
C
-B
qadmis
rle mengaib priwollot erT S
Quilons of qira ono mont aboog
eed indicator
yh from West
eril to Inioqbim srij
enisinoo MA
(6)
08 bas 8A aldao ni nolent or animaleb.gniweb slepe eld
260 km/h
D
1
D.
e
51
The figure gives the acceleration a versus time t for a particle moving along an x axis. The a-axis scale is set by as = 12.0 m/s². At t = -2.0
s, the particle's velocity is 11.0 m/s. What is its velocity at t = 6.0 s?
a (m/s²)
as
-2
0
2
t(s)
4
Two solid cylindrical rods AB and BC are welded together at B and loaded as shown. Knowing that the average normal stress must not
exceed 150 MPa in either rod, determine the smallest allowable values of the diameters d₁ and d2. Take P= 85 kN.
P
125 kN
B
125 kN
C
0.9 m
1.2 m
The smallest allowable value of the diameter d₁ is
The smallest allowable value of the diameter d₂ is
mm.
mm.
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