A student has an 80 g sample of a radioactive material that has a half-life of 20 seconds. How much material will he have left a
1 answer:
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1) Focal length
We can find the focal length of the mirror by using the mirror equation:
(1)
where
f is the focal length
is the distance of the object from the mirror
is the distance of the image from the mirror
In this case,
, while 
(the distance of the image should be taken as negative, because the image is to the right (behind) of the mirror, so it is virtual). If we use these data inside (1), we find the focal length of the mirror:
from which we find
2) The mirror is convex: in fact, for the sign convention, a concave mirror has positive focal length while a convex mirror has negative focal length. In this case, the focal length is negative, so the mirror is convex.
3) The image is virtual, because it is behind the mirror and in fact we have taken its distance from the mirror as negative.
4) The radius of curvature of a mirror is twice its focal length, so for the mirror in our problem the radius of curvature is:
We can find the focal length of the mirror by using the mirror equation:
where
f is the focal length
In this case,
from which we find
2) The mirror is convex: in fact, for the sign convention, a concave mirror has positive focal length while a convex mirror has negative focal length. In this case, the focal length is negative, so the mirror is convex.
3) The image is virtual, because it is behind the mirror and in fact we have taken its distance from the mirror as negative.
4) The radius of curvature of a mirror is twice its focal length, so for the mirror in our problem the radius of curvature is:
The Box's Acceleration : g sin θ
<h3>Further explanation </h3>Newton's 2nd law explains that the acceleration produced by the resultant force on an object is proportional and in line with the resultant force and inversely proportional to the mass of the object
∑F = m. a
F = force, N
m = mass = kg
a = acceleration due to gravity, m / s²
We plot the forces acting on the block (picture attached) according to the y-axis and the x-axis.
Because the motion of the block is in the same direction as the x-axis, ignoring the friction force with the inclined plane, then
