Answer:
Final vertical velocity = -29m/s 
Horizontal distance = 100m
Height = 20.41m
Explanation:
1. The vertical final velocity can be calculated thus: vy = vyo - gt
Where; 
vy = vertical velocity (m/s)
vyo = vertical initial velocity (20m/s)
g = acceleration due to gravity (9.8m/s²)
t = time (5s)
Hence, vy = vyo - gt
vy = 20 - (9.8 × 5)
vy = 20 - 49
vy = -29m/s 
2. x = V0 x t
Where;
x = horizontal distance (m)
Vo = initial velocity
t = time (s)
x = 20 × 5
x = 100m
3. Maximum height = (voy)²/2g
= 20²/ 2 × 9.8
= 400/19.6
= 20.41m
 
        
             
        
        
        
Answer:
Explanation:
work done by applied force 
= force x displacement
= 7.6 x 15 m 
= 114 J .
 
        
             
        
        
        
The electrostatic force between the two ions is 
Explanation:
The electrostatic force between two charged particle is given by Coulomb's law:

where
 is the Coulomb's constant
 is the Coulomb's constant
 are the two charges
 are the two charges
r is the separation between the two charges
In this problem, the ion of sodium has a charge of

while the ion of chlorine has a charge of

And the distance between the two ions is

Substituting, we find the electrostatic force between the two ions:

where the negative sign simply means that the force is attractive, since the two ions have opposite charge.
Learn more about electrostatic force:
brainly.com/question/8960054
brainly.com/question/4273177
#LearnwithBrainly
 
        
             
        
        
        
Answer:
Selenium is a semiconductor 
Explanation:
Selenium is a semiconductor. 
Elements in the column IV and VI of the periodic table are referred to as Semiconductor. 
Selenium lies in the column VI along with Tellurium
Some other elements of the column IV are silicon, germanium, and tin