Answer:
The time elapses until the boat is first at the trough of a wave is 4.46 seconds.
Explanation:
Speed of the wave, v = 59 km/h = 16.38 m/s
Wavelength of the wave, 
If f is the frequency of the wave. The frequency of a wave is given by :

The time period of the wave is given by :

We need to find the time elapses until the boat is first at the trough of a wave. So, the time will be half of the time period of the wave.

Hence, this is the required solution.
The synapse is actually the link between 2 neurons. Now when
an action potential contacts the synaptic knob of a neuron, the voltage-gate
calcium channels are unlocked, resulting in an influx of positively charged
calcium ions into the cell. This makes the vesicles containing
neurotransmitters, for example acetylcholine, to travel towards the
pre-synaptic membrane. When the vesicle arrives at the membrane, the contents
are released into the synaptic cleft by exocytosis. Neurotransmitters disperse
across the space, down to its concentration gradient, up until it reaches the
post-synaptic membrane, where it connects to the correct neuroreceptors. Connecting
to the neuroreceptors results in depolarisation in the post-syanaptic neuron as
voltage-gated sodium channels are also opened, and the positively charged
sodium ions travel into the cell. When adequate neurotransmitters bind to
neuroreceptors, the post-synaptic membrane overcame the threshold level of
depolarisation and an action potential is made and the impulse is transmitted.
A
The horizontal force cancels out. The two 4Ns go in opposite directions. So they don't affect the outcome.
The Vertical force is 6N up - 2 N down = 4 N Up
Answer 4 N up
B
The horizontal and vertical forces cancel out. Each gives 3N - 3N =0
The net force is 0
C
You only have horizontal forces on this one
5N - 3N = 2N
The answer is 2N to the right.