There are two types of electric charges; positive and negative
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Answer:
The Hydrostatic force is 
The location of pressure center is
Explanation:
From the question we are told that
The height of the gate is 
The weight of the gate is 
The height of the water is 
The density of water is 
Note used
for height of water and height of gate immersed by water since both have the same value
The area of the gate immersed in water is mathematically represented as

substituting values


The hydrostatic force is mathematically represented as

Where


So


The center of pressure is mathematically represented as

Where
is the moment of inertia of the gate which mathematically represented as

The
is the height of gate immersed in water
Thus


Given :
An electron moving in the positive x direction experiences a magnetic force in the positive z direction.
To Find :
The direction of the magnetic field.
Solution :
We know, force is given by :

Here, q = -e.

Now, for above condition to satisfy :

So, 
Therefore, direction of magnetic field is negative y direction.
Hence, this is the required solution.
Answer:
The speed of this light and wavelength in a liquid are
and 442 nm.
Explanation:
Given that,
Wavelength = 650 nm
Index refraction = 1.47
(a). We need to calculate the speed
Using formula of speed

Where, n = refraction index
c = speed of light in vacuum
v = speed of light in medium
Put the value into the formula



(b). We need to calculate the wavelength
Using formula of wavelength


Where,
= wavelength in vacuum
= wavelength in medium
Put the value into the formula


Hence, The speed of this light and wavelength in a liquid are
and 442 nm.
Kinetic energy is related to velocity by:
KE = (1/2)mv^2
solve for mass m
10 = (1/2)m(10)^2
10 = (1/2)m(100)
10= 50m
10/50 = m
1/5 = m
at 20 km/hr
KE = (1/2)(1/5)(20)^2
KE = (1/10)(400)
KE = 40 J