Answer:
(1) A hot drink cooling to room temperature.
(2) The combustion of natural gas.
Explanation:
The spontaneous process is the process in which there is a release of energy and moves towards lower energy and a more thermodynamically stable energy state. All the natural processes are spontaneous.
There are two processes which are spontaneous in the given question are:
(1) A hot drink cooling to room temperature: In this, there is a decrease in energy and also it is a natural process and we know that all the natural processes are spontaneous.
(2) The combustion of natural gas: The fire is an example of an exothermic reaction. The combustion is a combination of a decrease in energy and an increase in entropy. So, this process occurs spontaneously.
Answer:
Definition of direct current. : an electric current flowing in one direction only and substantially constant in value
Explanation:
Direct current (DC) is the one directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current.
Using moving water to produce electricity is an example of changing one form of energy into another form of energy.
Answer:
Explanation:
Moment of inertial of wheel I = M R²
Work done by force
= F d
It will be converted into rotational + linear kinetic energy
= 1/2 I ω² + 1/2 M V²
= 1/2 M R²ω² + 1/2 MV²
=1/2 MV²+1/2 MV²
MV²
MV² = Fd
V =
b )
acceleration of wheel
V² = 0 + 2 a d
a = V²/ 2d
= Fd / (M x 2d)
= F / 2M
if f be the force of friction
F - f = M a
= M x F / 2M
F - f = F /2
f = F /2
Friction force = F/2
Below are the answers:
a. There is a constant magnetic Feld, which means B is constant, so we can rewrite the change in fux as above.Because ΔA is positive, there will be a negative emf in the loop, corresponding to an induced magnetic momentpointing to the left on the page. The current in the loop will be into the page at the top and out of the page at<span>the bottom
</span>V=-Δφ/ Δt = -B·ΔA/ Δ<span>t
b. </span>As the loop’s radius is increasing, we can think about individual electrons in the wire loop as moving radially<span>outward. We’ll consider one in the top of the loop (which is moving up the page). Using the Lorentz ²orce Law
</span>F=q(~v⇥~B)=qvB(ˆy⇥ˆx)=-qvB<span>ˆ
</span>Constant forces pointing into the center of the loop will result in circular orbits (around the wire). Because the<span>force is pointing into the center of the loop, we know we have positive current at that point (into the page).</span>