WHY DOES EVERY IMAGE DOES NOT MAKE ON FOCUS ALWAYS we all know that light from a point go to different direction so there is possibility that few light will also travel parallel to each other and fall on concave mirror .from different point few light will travel also parallel, so why does not every image not made on focus in concave mirror

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

On a horizontal frictionless surface, a small block with mass 0.200 kg has a collision with a block of mass 0.400 kg. immediately after the collision, the 0.200 kg block is moving at 12.0 m/s in the direction 30° north of east and the 0.400 kg block is moving at 11.2 m/s in the direction 53.1° south of east. use coordinates where the +x-axis is east and the +y-axis is north.(a) what is the total kinetic energy of the two blocks after the collision (in ) what is the x-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your ) what is the y-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your answer.)

Which of the following is a measure of the amount of light a star directly emits?               a.  luminosity    b.  intensity    c.  wavelength    d.  brightness