You could answer this right away IF you knew the length of each wave, right ?
Well, Wavelength = (speed) / (frequency).
Speed = 3 x 10⁸ m/s (the speed of light)
and
Frequency = 90.9 x 10⁶ Hertz.
So the length of each wave is 3 x 10⁸ / 90.9 x 10⁶ meters.
To answer the question, see how many pieces you have to cut
that 1.5 km into, in order for each piece to be 1 wavelength.
It'll be
(1,500 meters) divided by (3 x 10⁸ meters/sec) / (90.9 x 10⁶ Hz)
To divide by a fraction, flip the fraction and then multiply:
(1500 meters) times (90.9 x 10⁶ Hz)/(3 x 10⁸ meters/sec)
= 454.5
We can solve the problem by using conservation of momentum.
The player + ball system is an isolated system (there is no net force on it), therefore the total momentum must be conserved. Assuming the player is initially at rest with the ball, the total initial momentum is zero:

The total final momentum is:

where
is the momentum of the player and
is the momentum of the ball.
The momentum of the ball is: 
While the momentum of the player is:
, where M=59 kg is the player's mass and vp is his velocity. Since momentum must be conserved,

so we can write

and we find

and the negative sign means that it is in the opposite direction of the ball.
Answer:
- <u>First choice:</u><u><em> Because the mass of the cannon ball is much less than the cannon</em></u>
Explanation:
Indeed, <em>Newton's Third Law</em>, i.e. the action-reaction law, states that any action (force) will have a reaction (force) of same magnitude but opposite direction.
That means that when a cannon goes off the cannon ball exerts a force on the cannon and the cannon exerts the same force back on the cannon ball.
To find out how much the cannon ball and the cannon itsel move, you must consider Newton's second law.
- F = m×a (force equal mass times acceleration).
Clearing the acceleration you get:
Then, since the mass is in the denominator and both the force that the cannon ball exerts on the cannon and the cannon exerts on the cannon ball are equal in magnitude, then the body that has the smaller mass (the cannon ball) will experience a greater acceleration, which is stated by the first choice: because the mass of the cannon ball is much less than the cannon.