12) Conduction. In fact, in conduction the heat is transferred when molecules collide with each other.
13) This is called thermal equilibrium. When we put two objects with different temperature in contact, their molecules have different kinetic energies. The molecules of the object with higher temperature are more energetic, and therefore they start to transfer part of their energy (by collisions) to the molecules of the object with lower temperature, until they reach a condition of equilibrium (i.e. the kinetic energies of the molecules of the two objects will be the same), and this happens when the two objects have same temperature.
14) Convection. Convection takes place in fluids: the heat is transferred by the movement of masses of fluids, from warmer regions to cooler regions.
15) Figure is missing.
16) Mechanical->Electrical. In fact, by walking through the room (movement, so mechanical energy) the body of the person acquired more electrostatic charges, and when it touches the doorknob a spark (electrical energy) takes place, because the charges accumulated on the body find a way to reach the ground throught the doorknob.
17) Law of Conservation of Energy. Indeed, it says that energy can convert into different forms, but the total energy of an isolated system must be conserved.
18) Electrical. In the cathode-ray-tube televisions, for instance, the image on the screen is produced by a current of electrons hitting the screen.
19) The chemical energy in the food is converted to mechanical energy to give the body energy to move. The energy for our body is in fact produced by the chemical reaction of the molecules of the food, and then it is used by our body to move, for instance.
20) Convection. Most of the heater uses water, which is heated and then it starts its flow to distribute the heat, therefore by convection.
21) Figure is missing.
22) The temperature of the steel decreases and the temperature of the water increases. In fact, as we said in number 13), the steel will transfer part of its energy to the water until they reach thermal equilibrium, so the temperature of the steel will decrease while the temperature of the water will increase.
23) It is given off as other forms of energy. In particular, it is converted into radiant energy: the bulb emits light, which is electromagnetic radiation, so the energy is re-emitted as radiation.
24) When two objects collide. For instance, assuming there is a body moving with speed v and another body stationary (with same mass), when they collide the first body transfers its kinetic energy to the second body, putting it in motion.
25) Electrical -> thermal. In a toaster, there is a resistance through which current flows. Due to the Joule effect, the current flowing through the resistor causes an increase of temperature of the resistor itself, therefore the energy of the current (electrical) is converted into thermal energy, which is then used to heat the toast.
Answer:
(a)
(b)
(c)
Explanation:
First change the units of the velocity, using these equivalents and
The angular acceleration the time rate of change of the angular speed according to:
Where is the original velocity, in the case the velocity before starting the deceleration, and is the final velocity, equal to zero because it has stopped.
b) To find the distance traveled in radians use the formula:
To change this result to inches, solve the angular displacement for the distance traveled ( is the radius).
c) The displacement is the difference between the original position and the final. But in every complete rotation of the rim, the point returns to its original position. so is needed to know how many rotations did the point in the 890.16 rad of distant traveled:
The real difference is in the 0.6667 (or 2/3) of the rotation. To find the distance between these positions imagine a triangle formed with the center of the blade (point C), the initial position (point A) and the final position (point B). The angle is between the two sides known. Using the theorem of the cosine we can find the missing side of the the triangle(which is also the net displacement):
Answer:
The loss in mechanical energy is 668.25 J
Explanation:
As per the question:
Mass of the base runner, m = 66 kg
Velocity of the runner, v = 4.5 m/s
Coefficient of friction,
Now,
The mechanical energy lost due to friction is provided by the work done in the form of the Kinetic energy of the runner:
Work done, W = Kinetic enrgy of the runner
W =
W =
Work done must be - 668.25 J as the runner slows down.