grade 9 revision u 1/2/3

scientist who founder the nebular theory -----------------------

• laplace

• fred holy

• bohr

• none

If a beam of parallel rays fall on the concave lens, and they parallel to the principal axis, so the rays pass through the concave lens

as if they come from ------------

• center

• focal length

• focus

• none

Compare between

2. Positive acceleration and negative acceleration (according to initial speed and final speed

What happens when...?

A light ray pass in the optical center of lens

What happens when...?

A cloud of gas remained and subject to cooling and contraction processes as modern theory.

The point that is in the middle of the reflecting surface of the spherical mirror.

A vision defects leads to formation of image behind the eye retina

The result of multiplying a speed of a moving object by time.

It contains all galaxies, stars, planets and living organism.

Write the function of:

Speedometers is in airplanes and cars.