The oldest way ... the way we've been using as long as we've been
walking on the Earth ... has been to use plants. Plants sit out in the
sun all day, capturing its energy and using it to make chemical compounds.
Then we come along, cut the plants down, and eat them. Our bodies
rip the chemical compounds apart and suck the solar energy out of them,
and then we use the energy to walk around, sing, and play video games.
Another way to capture the sun's energy is to build a dam across a creek
or a river, so that the water can't flow past it. You see, it was the sun's
energy that evaporated the water from the ocean and lifted it high into
the sky, giving it a lot of potential energy. The rain falls on high ground,
up in the mountains, so the water still has most of that potential energy
as it drizzles down the river to the ocean. If we catch it on its way, we
can use some of that potential energy to turn wheels, grind our grain,
turn our hydroelectric turbines to get electrical energy ... all kinds of jobs.
A modern, recent new way to capture some of the sun's energy is to use
photovoltaic cells. Those are the flat blue things that you see on roofs
everywhere. When the sun shines on them, they convert some of its
energy into electrical energy. We use some of what they produce, and
we store the rest in giant batteries, to use when the sun is not there.
Answer:
Voltage-gated calcium ion channels open, and calcium ions diffuse into the cell
Answer: 0.2m
Explanation: Firstly only the Rocket's Weight Compress the spring which can be found by
According to Hooks Law
The part b and c of this question is done in the attachment
Answer:
Given, Apparent weight(W₂)=4.2N
Weight of liquid displaced (u)=2.5N
Let weight of body in air = W₁
Solution,
U=W₁-W₂
W₁=4.2=2.5=6.7N
∴Weight of body in air is 6.7N
Answer:
1. Force = mass x acceleration - Newton
2. A planet moves faster in the part of its orbit nearer the Sun and slower when farther from the Sun, sweeping out equal areas in equal times - Kepler
3. For any force, there is an equal and opposite reaction force - Newton
.
4. An object moves at constant velocity if there is no net force acting upon it - Newton
5. The orbit of each planet about the Sun is an ellipse with the Sun at one focus - Kepler.
6. More distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationship p2-a3 - Kepler.
Explanation:
The three laws of planetary motion formulated by Johannes Kepler or Kepler's laws of planetary motion:
- The first law states that the planets move around the Sun in an elliptical orbit with the Sun at one of the foci.
- The second law states that the line segment joining a planet to the Sun sweeps out equal areas in equal time.
- The third law states that the square of the orbital period (p) of a planet is directly proportional to the cube of the mean distance (a) from the Sun (or semi-major axis of its orbit) i.e., p² is proportional to a³.
The three laws of motion formulated by Sir Isaac Newton or Newton's laws of motion:
- The first law, also known as the law of inertia states that an object at rest or moves at a constant velocity will remain at rest or keep moving at a constant velocity unless it is acted upon by a force.
- The second law states that the total force (F) applied on an object is directly related to the acceleration (a) of that object produced by the applied force and the mass (m) of the object, i.e., F = ma (assuming the mass m is constant).
- The third law, also known as the law of action and reaction states that when an object exerts a force on another object, then the latter exerts a force equal in magnitude and opposite in direction on the former object i.e., for every action, there is an equal and opposite reaction. The example includes the recoiling of a gun when it fires a bullet forward.
