Power = (work done) / (time to do the work)
= (21,000 Joules) / (30 seconds)
= (21,000 / 30) joule/sec
= 700 watts
The examples may be;
making yogurt; If you heat beyond 130F you kill the cultures. The higher the temperature up until that point the faster it cultures until you close in on killer temperature.
Mixing 2 part epoxy; Keep it cool and the reaction time is delayed. On the other hand, heat it up and epoxy reacts quicker. In the winter time and close to 35 Degrees, the reaction time for cement to harden can take 400% more time to set.
Answer:
Raising the highest point of the track to a higher point
Explanation:
When the rubber ball starts its motion, from the highest point of the track, it has only gravitational potential energy, given by:
where m is the mass of the ball, g is the gravitational acceleration and h is the height above the ground.
As the ball descends the track, this potential energy is partially converted into kinetic energy, given by:
(where m is the mass and v is the speed)
and partially lost as heat, due to the friction between the surface of the track.
As a consequence, the higher the initial height of the track (h in the formula), the greater will be the kinetic energy gained by the ball. A greater kinetic energy means a larger velocity, which also means that the ball will cover a longer distance before stopping.
To solve this problem it is necessary to apply the concepts related to electromotive force or induced voltage.
By definition we know that the induced emf in the loop is equal to the negative of the change in the magnetic field, that is,
Where A is the area of the loop, B the magnetic field and t the time.
Replacing with our values we have that
Therefore the thermal energy produced is given by
The thermal energy produced in the loop is