Answer:
buoyant force on the block due to the water= 10 N
Explanation:
We know that
buoyant force(F_B) on a block= weight of the block in air (actual weight) - weight of block in water.
Given:
A block of metal weighs 40 N in air and 30 N in water.
F_B = 40-30= 10 N
therefore, buoyant force on the block due to the water= 10 N
A) d. 10T
When a charged particle moves at right angle to a uniform magnetic field, it experiences a force whose magnitude os given by

where q is the charge of the particle, v is the velocity, B is the strength of the magnetic field.
This force acts as a centripetal force, keeping the particle in a circular motion - so we can write

which can be rewritten as

The velocity can be rewritten as the ratio between the lenght of the circumference and the period of revolution (T):

So, we get:

We see that this the period of revolution is directly proportional to the mass of the particle: therefore, if the second particle is 10 times as massive, then its period will be 10 times longer.
B) 
The frequency of revolution of a particle in uniform circular motion is

where
f is the frequency
T is the period
We see that the frequency is inversely proportional to the period. Therefore, if the period of the more massive particle is 10 times that of the smaller particle:
T' = 10 T
Then its frequency of revolution will be:

Answer:
<em>x < 4</em>
Explanation:
<u>Inequalities</u>
The inequalities relate expressions using signs different from the equal sign, like "<" or "<" among others.
They can be treated as a normal equation but in case of directional relationals, care must be taken when multiplying or dividing by negative numbers.
The inequality given in the question is
3x - 4 > 4x - 8
Subtracting 3x in both sides
3x - 4 -3x > 4x - 8 -3x
Simplifying
-4 > x - 8
Adding 8
-4 + 8 > x - 8 + 8
Simplifying
4 > x
The solution comes by flipping both sides and the inequality sign
x < 4