Downward force of magnitude 5 N is exerted on the book by the force of <em>gravity</em>. We call that the "weight" of the book.
At the same time, upward force of 5 N is exerted on the book by the table. This one is called the "normal force".
Since the vertical forces on the book are 'balanced' (add up to zero), the book just lays there on the table, and does not accelerate.
Frequency
Amplitude
Wavelength
Speed
The lowest point, where the amount of energy is the greatest
Answer:
For a plant cell: The cell wall and the cell membrane
For animal cells: Just the cell membrane

The velocity at time
is

Take two vectors that point in the positive
and positive
directions, such as
and
. The dot products of the velocity vector with
and
are

and

We want the angles between these vectors to be 45º, for which we have
. So



When
, the velocity vector is equal to the zero vector, which technically has no direction/doesn't make an angle with any other vector. So the only time this happens is for
