Answer:
Part(a): The frequency is
.
Part(b): The speed of the wave is
.
Explanation:
Given:
The distance between the crests of the wave,
.
The time required for the wave to laps against the pier, 
The distance between any two crests of a wave is known as the wavelength of the wave. So the wavelength of the wave is
.
Also, the time required for the wave for each laps is the time period of oscillation and it is given by
.
Part(a):
The relation between the frequency and time period is given by

Substituting the value of
in equation (1), we have

Part(b):
The relation between the velocity of a wave to its frequency is given by

Substituting the value of
and
in equation (2), we have

Answer:
2.9 A
Explanation:
L = 16 cm = 0.16 m
B = 0.19 T
m = 9 g = 0.009 kg
Let the minimum current be i.
Magnetic force is balanced by the gravitational force
B x i x L = m x g
0.19 x i x 0.16 = 0.009 x 9.8
i = 2.9 A
In longitudinal waves the places where the coils are bunched together are called *
Compressions
Answer:
the third law (for every action there is an equal and opposite reaction).
Explanation:
The skateboarder pushes backwards on the road (that is he applies a force on the road in a direction opposite the direction of intended motion). By Newton's third law, this action of the skateboarder causes an equal reaction of the road on the skateboarder in the opposite direction. Newton's third law states that action and reaction are equal but opposite in direction. So, the road in response to this backward force pushes the skateboarder in the forward direction causing the skateboarder and the skateboard to move in the forward direction.