All magnets have north and south poles. Opposite poles are attracted to each other, while the same poles repel each other. When you rub a piece of iron along a magnet, the north-seeking poles of the atoms in the iron line up in the same direction. The force generated by the aligned atoms creates a magnetic field.
Answer:
-6112.26 J
Explanation:
The initial kinetic energy, is given by
} where m is the mass of a body and is the initial velocity
The final kinetic energy, is given by
where is the final velocity
Change in kinetic energy, is given by
Since the skater finally comes to rest, the final velocity is zero. Substituting 0 for and 12.6 m/s for and 77 Kg for m we obtain
From work energy theorem, work done by a force is equal to the change in kinetic energy hence for this case work done equals <u>-6112.26 J</u>
<u>F = M A </u> (Newton's #2)
Force = (0.15 kg) (12 m/s²)
Force = (0.15 · 12) (kg·m/s²)
<em>Force = 1.8 Newtons</em>
The motion of the light is a uniform motion with constant speed
, therefore we can use the basic relationship between speed, space and time:
(1)
where S is the distance covered and t is the time taken. The light takes t=1.3 s to travel from the moon to Earth, therefore by rearranging eq.(1) we can find the distance between the Moon and the Earth: