What is the maximum efficiency of a heat engine whose operating temperatures are 590 ?c and 325 ?c?
1 answer:
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Answer:
Under the reasonable assumption that the brick has more mass than the feather, the brick experiences a greater force of air friction.
Explanation:
<u>Objects at terminal velocity</u>, only under the influence of gravity, have maximized their speed and <u>have an acceleration of zero</u>. Thus, neither object is accelerating.
Recall Newton's second law:
Since acceleration for each object is zero, the sum of the force acting on each of those objects must also be zero.
Since the only forces acting on the objects are gravity and the force of air friction, in order to zero out, <u>the force of air friction must be equal in magnitude and opposite in direction to the force of gravity</u>.
Recall that near the surface of the earth, , so <u>the Force of Gravity acting on an object is directly proportional to the object's mass</u>. <em>(A similar argument could be made even if this were not taking place on the surface of the earth, so long as the objects were the same distance from the object providing gravitational influence).</em>
If the masses of the objects are different, <u>the object with the greater mass will experience</u> a larger force of gravity, and hence <u>a larger force of air friction</u> at terminal velocity.
Under the reasonable assumption that the brick has more mass than the feather, the brick experiences a greater force of air friction.
Answer:
B = 0.024T positive z-direction
Explanation:
In this case you consider that the direction of the motion of the electron, and the direction of the magnetic field are perpendicular.
The magnitude of the magnetic force exerted on the electron is given by the following formula:
(1)
q: charge of the electron = 1.6*10^-19 C
v: speed of the electron = 1.6*10^7 m/s
B: magnitude of the magnetic field = ?
By the Newton second law you also have that the magnetic force is equal to:
(2)
m: mass of the electron = 9.1*10^-31 kg
a: acceleration of the electron = 7.0*10^16 m/s^2
You solve for B from the equation (2):
The direction of the magnetic field is found by using the right hand rule.
The electron moves upward (+^j). To obtain a magnetic forces points to the positive x-direction (+^i), the direction of the magnetic field has to be to the positive z-direction (^k). In fact, you have:
-^j X ^i = ^k
Where the minus sign of the ^j is because of the negative charge of the electron.
Then, the magnitude of the magnetic field is 0.024T and its direction is in the positive z-direction