The unknown substance can be lithium, which has a specific heat capacity of approximately 
.
Explanation:
When heat energy is supplied to a certain substance, the temperature of the substance increases according to the equation:
where
Q is the amount of energy supplied
m is the mass of the sample
is the specific heat capacity of the substance
is the change in temperature
In this problem, we have
m = 4.9 g is the mass
Q = 668.85 J is the specific heat capacity
is the change in temperature
Solving for , we find the specific heat capacity of the substance:
Looking at tables of specific heat capacity, we can see that the unknown substance can be lithium, which has a specific heat capacity of approximately .
Learn more about specific heat capacity:
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The medium is the component of communication through which information is transferred. The correct option in the given question is option "c". Medium is actually the means through which communication is done. It can be a an oral message or written message or it can be nonverbal or symbolic. Any kind of message transmission requires a medium and without an medium no message can be transmitted. Whenever people talk on the telephone or write a letter, there has to be a medium for transmitting the message to the person on the other side.
Water gets to the leaves in the tops of the tallest trees by something called the cohesion-tension theory. Water has two very unique properties called adhesion and cohesion. Cohesion is the tendency of water molecules to stick together with one another. The water sticks together, leaving no room for air, strengthening the "force" of the water going up the tree. The water also sticks to the sides of the xylem inside the tree. In addition to these properties, there are also the factors of negative and positive water potential. For more information, look up more details of the cohesion-tension theory.
Answer:
Long sight occurs when the eyeball is too short or the lens is too thin, or both. As a result, light rays from near objects are focused behind the retina because the light rays are not converged enough. The image formed on the retina is therefore out of focus.
To correct this problem, people can wear glasses with convex lenses. Light rays from near objects are converged by the convex lenses before entering the eyes, so that light can be focused on the retina to form a sharp image. Additionally, long sight can also be corrected by surgical methods such as LASIK.
Answer:
a. 21.68 rad/s b. 30.78 m/s c. 897 rev/min² d. 1085 revolutions
Explanation:
a. Its angular speed in radians per second ω = angular speed in rev/min × 2π/60 = 207 rev/min × 2π/60 = 21.68 rad/s
b. The linear speed of a point on the flywheel is gotten from v = rω where r = radius of flywheel = 1.42 m
So, v = rω = 1.42 m × 21.68 rad/s = 30.78 m/s
c. Using α = (ω₁ - ω)/t where α = angular acceleration of flywheel, ω = initial angular speed of wheel in rev/min = 21.68 rad/s = 207 rev/min, ω₁ = final angular speed of wheel in rev/min = 1410 rev/min = 147.65 rad/s, t = time in minutes = 80.5/60 min = 1.342 min
α = (ω₁ - ω)/t
= (1410 - 207)/(80.5/60)
= 60(1410 - 207)/80.5
= 60(1203)80.5
= 896.65 rev/min² ≅ 897 rev/min²
d. Using θ = ωt + 1/2αt²
where θ = number of revolutions of flywheel. Substituting the values of the variables from above, ω = 207 rev/min, α = 896.65 rev/min² and t = 80.5/60 min = 1.342 min
θ = ωt + 1/2αt²
= 207 × 1.342 + 1/2 × 896.65 × 1.342²
= 277.725 + 807.417
= 1085.14 revolutions ≅ 1085 revolutions
