<span>The initial momentum of the boy is equal to the boy/boat because the final velocity of the boat is less than the initial velocity of the boy.</span>
Electroreception is limited to aquatic environments because on here is the resistivity of the medium is low enough for electric currents to be generated as the result of electric fields of biological origin. In air, the resistivity of the environment is so high that electric fields from biological sources do not generate a significant electric current. Electroreceptor are found in a number of species of fish, and in at least one species of mammal, the Duck-Billed platypus.
In order to increase muscular endurance, it is important to take part in activities that increase the size of muscle cells and the amount of blood that is delivered to the cells<span>. The increased size of the muscle cells reuires them to contract less to accomplish the same task; moreover, the increased blood flow helps deliver oxygen and nutrients to the blood.</span>
Explanation:
The given data is as follows.
Resistance (R) = 1200 ohm, Area (A) =
m (as
)
Diameter (d) = 2.3 mm =
m
First, we will calculate the length as follows.
R =
Here,
= resistivity of aluminium = 
Putting the given values above and we will calculate the value of length as follows.
R =
1200 = 
L = 
As the circumference of circular wire = 
or, =
= 
And, number of turns will be calculated as follows.
No. of turns × Circumference = Length of wire
No. of turns × 
= 
Thus, we can conclude that
turns of wire are needed.
Answer:
v = 6.79 m/s
Explanation:
It is given that,
Mass of a train car, m₁ = 11000 kg
Speed of train car, u₁ = 21 m/s
Mass of other train car, m₂ = 23000 kg
Initially, the other train car is at rest, u₂ = 0
It is a case based on inelastic collision as both car couples each other after the collision. The law of conservation of momentum satisied here. So,

V is the common velocity after the collisions

So, the two car train will move with a common velocity of 6.79 m/s.