Answer:
Kinetic energy is greatest at the lowest point of a roller coaster and least at the highest point.
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Answer:
840 W
Explanation:
The energy expended in hoisting the diver up is given by

<em>m</em> is the mass of the diver, <em>g </em>is the acceleration due to gravity and <em>h</em> is the height.
Using the values in the question and taking <em>g</em> as 9.8 m/s²,

The power is given by

<em>t</em> is the time.
Hence,

In step 1, to increase the potential energy, the iron will move towards the electromagnet.
In step 2, to increase the potential energy, the iron will move towards the electromagnet.
<h3>Potential energy of a system of magnetic dipole</h3>
The potential energy of a system of dipole depends on the orientation of the dipole in the magnetic field.

where;
is the dipole moment- B is the magnetic field


Increase in the distance (r) reduces the potential energy. Thus, we can conclude the following;
- In step 1, to increase the potential energy, the iron will move towards the electromagnet.
- In step 2, when the iron is rotated 180, it will still maintain the original position, to increase the potential energy, the iron will move towards the electromagnet.
Learn more about potential energy in magnetic field here: brainly.com/question/14383738
The kinetic energy of the object just after it starts its motion from the Earth surface is

where m is the object mass and

its initial speed.
When it reaches its maximum height, the object speed is zero and all its kinetic energy converted into gravitational potential energy, which is

where

and h is the maximum height reached by the object.
Since the energy of the object must be conserved, K=U, therefore we can write

and we can solve to find h, the maximum height: