Answer:
1.53m
Explanation:
Given parameters:
Mass of box = 3kg
Gravitational potential energy = 45J
Unknown
Height of the box = ?
Solution:
To solve this problem;
Gravitational potential energy = mgh
m is the mass
g is the acceleration due to gravity
h is the height
45 = 3 x 9.8 x h
h = 1.53m
Because one pole of the Earth's axis of rotation (the North one) points
almost exactly toward Polaris.
If Polaris had a pimple or a bump somewhere on its edge, you'd see
the bump rotate around the whole edge, like a clock, once a day. But
the whole star appears to stay in one place, because our axis points to it.
Velocity is a vector meaning it includes an objects speed and direction.
The flow of Direct current (DC) is constant and flows in one direction. Most digital electronics make use of DC. Alternating current (AC) periodically flows in reverse and is mostly used to deliver power to houses, buildings and the like. With that alone, you can already rule out A, C and D.
The answer would then be B. constant, periodically reversing.
