I would assume you answer them by doing the math required.
<span>If coal is stacked near mines, the most likley thing that will happen is that rain watter will carry contaminants in coal into durface water. When rain falls on coal, it erodes it just like any other rock. So amounts of coal can be washed out of its holding area and into surface *and* groundwater. Correct answer:D</span>
Density because any object that is more dense than water (density of 1. I forget the units) sinks, and any object less dense than water floats.
Answer:
The magnitude of displacement is 56.54 m
The direction of the displacement is along the line joining the two vectors.
Explanation:
The resultant displacement is always the line joining the initial and final position of the vectors.
As in figure,
the vector AB = 35 m
the vector BC = 15 m
the angle between AB and AC = 25' (minutes)
the resultant vector AC = ?
The resultant vector is given by the formula
AC² = AB² + BC² + 2 AB BC Cos θ
Substituting the values in the equations,
AC² = 35² + 15² + 2 x 35 x 15 x Cos 25'
= 56.54
Therefore, the magnitude of displacement is 56.54 m
The direction of the displacement is along the line joining the two vectors.
"2 km/hr/s" means that in each second, its engines can increase its speed by 2 km/hr.
If it keeps doing that for 30 seconds, its speed has increased by 60 km/hr.
On top of the initial speed of 20 km/hr, that's 80 km/hr at the end of the 30 seconds.
This whole discussion is of <em>speed</em>, not velocity. Surely, in high school physics,
you've learned the difference by now. There's no information in the question that
says anything about the train's <em>direction</em>, and it was wrong to mention velocity in
the question. This whole thing could have been taking place on a curved section
of track. If that were the case, it would have taken a team of ace engineers, cranking
their Curtas, to describe what was happening to the velocity. Better to just stick with
speed.
