Comets are like "dirty snowballs"; frozen gasses with dust and rocks in them. Each pass near the Sun causes the comet's nucleus to be exposed to intense sunlight, which causes some tiny fraction of the gas to evaporate and carry some of the dust and rock away into space. The gas and dust, near the Sun, cause the comet's "tail", and repeated passes cause dust and rock to spread out along most of the orbit of a comet. When the Earth enters one of these trails of old comet dust, we have meteor showers.
<span>On rare occasions, comets break apart or even more rarely, crash into planets. In 1994, the comet Shoemaker-Levy 9 broke apart and then collided with the planet Jupiter.</span>
Answer:
Review each answer in the explanation part
Explanation:
Identify a problem or need = Aerospace engineers need a lightweight material to build a jet
Note: Identify a problem is related always with a need.
After identify the problem the next stage is the design
Design a solution = Engineers determine what features the material must have.
Note: The design process implies the choice of the materials and the proper numeric calculations.
Implement the solution = Engineers test a carbon - plastic compound in a wind tunnel.
Note: after the design, the following process is the built of the equipment and the different tests.
Evaluate the solution = The carbon-plastic compound is redesigned to save maximun energy.
Note: After testing, you enter a part of re-design that means making improvements to the already constructed.
Answer:
More work done with less power
The increase in gravitational energy is the same as the height which is a function of gravitational energy is the same in both cases
Explanation:
Climbing the mountain in zigzag pattern is easier because
1. The time it takes to climb increases so that the required power or rate of doing work decreases
2. Climbing in zigzag pattern affords the use of leverages by the sides
3. Similar mechanical power gain and efficiency from using a drive screw instead of a nail to fasten items together can be achieved
The increase in gravitational energy is the same gravitational energy ~ mass × gravity ×height
The general formula to calculate the work is:
where F is the force, d is the displacement of the couch, and 
is the angle between the direction of the force and the displacement. Let's apply this formula to the different parts of the problem.
(a) Work done by you: in this case, the force applied is parallel to the displacement of the couch, so 
and 
, therefore the work is just equal to the product between the horizontal force you apply to push the couch and the distance the couch has been moved:
(b) work done by the frictional force: the frictional force has opposite direction to the displacement, therefore 
and 
. Therefore, we must include a negative sign when we calculate the work done by the frictional force:
(c) The work done by gravity is zero. In fact, gravity (which points downwards) is perpendicular to the displacement of the couch (which is horizontal), therefore 
and 
: this means
.
(d) Work done by the net force:
The net force is the difference between the horizontal force applied by you and the frictional force:
And the net force is in the same direction of the displacement, so and and the work done is
