When 150 joules of work is done on a system by an external force of 15 newtons in 20. seconds, the total energy of that system i
1 answer:
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Answer:
A) Its density will decrease
Explanation:
When an object is heated, its volume increases. This is due to the fact that the particles in the medium vibrate more (if it is a solid) or they move more (if it is a liquid or a gas), therefore they tend to occupy a larger space.
At the same time, the mass of the object does not change, because the mass just represents the amount of matter contained in the object, so it does not increase/decrease at different temperatures.
The density of an object is defined as the ratio between the mass (m) and the volume (V):
We said that the mass remains unchanged while the volume increases: since the density is inversely proportional to the volume, this means that the density decreases.
Answer:
(b) EAST
Explanation:
you can assume that the magnetic field points rightward, that is, in the positive x direction (NORTH). Furthermore, you can assume that the direction of the motion of the electron is in the positive y direction. Hence, you have:
You use the Lorentz formula to known which is the direction of the magnetic force over the electron:
which implies the cross product between the unitary vecors j and i, that is
(WEST)
However, the minus sign of the charge of the electron changes the direction 180°. Hence, the direction is k. That is, to the EAST