Answer:
* roller skates and ice skates.
* roller coaster
Explanation:
One of the best examples for this situation is when we are skating, in the initial part we must create work with a force, it compensates to move, after this the external force stops working and we continue movements with kinetic energy, if there are some ramps, we can going up, where the kinetic energy is transformed into potential energy and when going down again it is transformed into kinetic energy. This is true for both roller skates and ice skates.
Another example is the roller coaster, in this case the motor creates work to increase the energy of the car by raising it, when it reaches the top the motor is disconnected, and all the movement is carried out with changes in kinetic and potential energy. In the upper part the energy is almost all potential, it only has the kinetic energy necessary to continue the movement and in the lower part it is all kinetic; At the end of the tour, the brakes are applied that bring about the non-conservative forces that decrease the mechanical energy, transforming it into heat.
Answer:
Explanation:
As per Ampere's law the magnetic field at the surface of the wire is given as
here we have
so we will have
now again we use same value of current but wire with double the diameter
so the magnetic field at the surface is given as
so we have
Answer: Option (b) is the correct answer.
Explanation:
It is known that when a ray of light tends to travel from a denser to rarer medium then there occurs total internal reflection.
For a denser medium the refractive index is greater than that of a rarer medium. This means that for the given situation refractive index of medium 
is greater than medium 
.
this also means that incident angle must be greater than the critical angle of the medium.
Thus, we can conclude that the statement > must be true for total internal reflection to occur.
Acceleration can be any change in speed, increasing or decreasing.
You haven't said whether the ball is speeding up or slowing down.
If its acceleration is positive ... speed is increasing ... then in 2.5 seconds,
it GAINS (0.5 m/s² x 2.5 sec) = 2.5 m/s of speed. Added to its initial
speed of 2.0 m/s, it ends up moving at 4.5 m/s.
If its acceleration is negative ... speed is decreasing ... then in 2.5 seconds,
it LOSES (0.5 m/s² x 2.5 sec) = 2.5 m/s of speed. Added to its initial
speed of 2.0 m/s, it ends up moving at -0.5 m/s. That means that it ends up
moving in the opposite direction compared to its direction at the beginning of
the change.
