Hi there!
(a)
Recall that:

W = Work (J)
F = Force (N)
d = Displacement (m)
Since this is a dot product, we only use the component of force that is IN the direction of the displacement. We can use the horizontal component of the given force to solve for the work.

To the nearest multiple of ten:

(b)
The object is not being displaced vertically. Since the displacement (horizontal) is perpendicular to the force of gravity (vertical), cos(90°) = 0, and there is NO work done by gravity.
Thus:

(c)
Similarly, the normal force is perpendicular to the displacement, so:

(d)
Recall that the force of kinetic friction is given by:

Since the force of friction resists the applied force (assigned the positive direction), the work due to friction is NEGATIVE because energy is being LOST. Thus:

In multiples of ten:

(e)
Simply add up the above values of work to find the net work.

Nearest multiple of ten:

(f)
Similarly, we can use a summation of forces in the HORIZONTAL direction. (cosine of the applied force)



Nearest multiple of ten:

Answer:
A
Explanation:
Please see the attached picture for the full solution.
Since we are only concerned about the decrease in gravitational potential energy of the car, we look at the decrease in height of the car as it moves from point X to point Y, instead of the distance travelled by the car.
Answer:
Unknown
Explanation:
By definition, we can't observe what's inside there, because no light – no information of any kind – can escape a black hole. But astrophysical theories suggest that, at the core of a black hole, all the black hole's mass is concentrated into a tiny point of infinite density. This point is known as a singularity.
Answer: The correct answer is "trumpet".
Explanation:
Resonance occurs when the applied frequency on the object is equal to the natural frequency of the object.
Wind instruments use resonance in the air column to amplify the sound. It makes the sound louder. Sound is produced by using lips or vibrating reeds or buzzing sound into the mouthpiece.
Therefore, resonance in air column is used in trumpet musical instruments.
The planetary temperature energy balance is obtained by radiating back the absorbed radiation energy from outer-space, by the planet and thus acquiring thermal equilibrium.
What is the process of attaining thermal equilibrium by Earth?
The Stefan-Boltzmann law states that the more the temperature a planet has, the more it will radiate out to reach thermal equilibrium.
We know that outer space contains large masses of radiative energy freely distributed in its vast expanse. A small fraction of this energy is absorbed by the Earth through the atmosphere, surface land, clouds etc.
Now, radiative balance is achieved when a planet's surface continuously warms up until it reaches its peak at which point the same amount of absorbed energy can then be radiated back to space. The relative amount of energy radiated back by a planet is dependent upon the size of the planet.
A colder planet relatively absorbs lower amount of radiation energy from space. In some time, as the planet heats up enough, the energy is radiated back to the space attaining thermal equilibrium.
Learn more about Stefan-Boltzmann law here:
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