Acceleration means speeding up, slowing down, or changing direction. The graph doesn't show anything about direction, so we just have to examine it for speeding up or slowing down ... any change of speed.
The y-axis of this graph IS speed. So the height of a point on the line is speed. If the line is going up or down, then speed is changing.
Sections a, c, and d are all going up or down. Section b is the only one where speed is not changing. So we can't be sure about b, because we don't know if the track may be curving ... the graph can't tell us that. But a, c, and d are DEFINITELY showing acceleration.
Answer: The machine must apply the force over a shorter distance. That's because a machine doesn't change the amount of work and work equals force times distance. Therefore, if force increases, distance must decrease
FALSE
HOPE THIS HELPS
Before Pluto was discovered, it was predicted. Astronomers had observed that massive objects can affect the orbits of its neighbors, and, after seeing deviations in the orbits of Uranus and Neptune, assumed something substantial existed beyond their orbits.
When Pluto was spotted, it was thought to be the predicted object and was identified as a ninth planet.
A few decades later, astronomers started discovering more and more objects around other stars and didn’t know whether to call them planets or not. There appeared to be a need to define what a planet means, and that led to what some people consider Pluto’s demotion to a dwarf planet.
The International Astronomical Union decided that full-sized planets must orbit the sun, have a round shape, and have cleared their orbits of other objects. Pluto fulfills the first two criteria, but not the third.
It still goes around the sun, it’s round enough, it’s got moons, and behaves like a planet, but the idea is that Pluto did not form the same way as the rest of the planets. Pluto’s orbit is both eccentric and inclined more than the rest of the planets by about 17 degrees. That’s suggests something is different about this object.
This debate about whether to call it a planet or not is silly, because it doesn’t matter to Pluto what you call it. It is an interesting object, goes around the sun, and shows geology and an atmosphere.
There’s a tendency to define objects based on what they are now, but nothing is constant in the universe. There are some issues with the nomenclature, and a definition today may not apply to the same object tomorrow.
The harbour contains salt water while the river contains
fresh water. So assuming that the densities of fresh water and salt water are:
density (salt water) = 1029 kg / m^3
density (fresh water) = 1000 kg / m^3
The amount of water (in mass) displaced by the barge
should be equal in two waters.
mass displaced (salt water) = mass displaced (fresh
water)
Since mass is also the product of density and volume, therefore:
<span>[density * volume]_salt water = [density * volume]_fresh
water ---> 1</span>
First we calculate the amount of volume displaced in the harbour
(salt water):
V = 3.0 m * 20.0 m * 0.70 m
V = 42 m^3 of salt water
Plugging in the values into equation 1:
1029 kg / m^3 * 42 m^3 = 1000 kg/m^3 * Volume fresh water
Volume fresh water displaced = 43.218 m^3
Therefore the depth of the barge in the river is:
43.218 m^3 = 3.0 m * 20.0 m * h
<span>h = 0.72 m (ANSWER)</span>
Answer:
KE + PE = KE + PE
Explanation:
In a closed system, the mechanical energy of the system is constant.
Mechanical energy is given by the sum of kinetic energy and potential energy; mathematically:
U = KE + PE
where
KE is the kinetic energy
PE is the potential energy
This means that if we consider two situations, one at the beginning and one at the end, the value of U will not change if the system is closed; this means that the sum KE + PE will remain the same, so we can write:
KE + PE = KE + PE
