When you touch a cold piece of ice with your finger, energy flows
A) from your finger to the ice.
B) from the ice to your finger.
C) actually, both ways.
Answer: A
You might also like to view...
It has been proposed that highly concentrating solar power such as the one below can be used to process materials economically when it is desirable to heat the material surface rapidly without significantly heating the bulk. In one such process for case hardening low-cost carbon steel, the surface of a thin disk is to be exposed to concentrated solar flux.
The distribution of absorbed solar flux on the disk is given by
where r is the distance from the disk axis and q''max and Ro are parameters that describe
the flux distribution. The disk diameter is 2Rs, its thickness is Zs, its thermal conductivity
is k and its thermal diffusivity is a. The disk is initially at temperature Tinit and at time
t = 0 it is suddenly exposed to the concentrated flux. Derive the set of explicit difference
equations needed to predict how the disk temperature distribution evolves with time. The
edge and bottom surface of the disk are insulated and reradiation from the disk is
neglected.
GIVEN
- Steel disk exposed to concentrated solar flux
FIND
(a) Explicit difference equations that describe evolution of disk temperature
If an astronaut takes an object to the moon the following is true (choose only one)
A. both the mass and the weight of the object will change. B. both the mass and the weight of the object will be the same. C. the weight will change but the mass will be the same. D. the mass will change but the weight will be the same.
A Carnot heat engine operates between 400 K and 500 K. Its efficiency is:
A. 20% B. 25% C. 44% D. 79% E. 100%
What does the theory neutrino oscillation explain?
a. Why more electron neutrinos leave the Sun and more muon and tau neutrinos reach the Earth. b. Why exactly 1/3 of the neutrinos reaching Earth are electron neutrinos. c. Why more muon and tau neutrinos leave the Sun and more electron neutrinos reach the Earth. d. Why more electron and muon neutrinos leave the Sun and more tau neutrinos reach the Earth. e. Why the same proportion of neutrinos reach the Earth as leave the Sun.