The  frictional force will be 0.22N.
<h3>What is Frictional force?</h3>
Frictional force is the force generated between two surfaces that are in contact and slide against each other. 
Given,
Weight=4N 
mass =4.9/9.8=0.5kg 
Hieght =30m 
velocity=24m/s 
Acceration , v²-u²=2as 
24²/2×30 =a , u is zero 
  a= 1.5m/s² 
By Using conservation  of energy ,
30F+1/2mv²=mgh 
30F=1150-144
F= 6/30 
F=0.2N 
The force will be 0.2N 
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Answer:
(a) charge q=5.33 nC
(b) charge density σ=10.62 nC/m²
Explanation:
Given data
radius r=0.20 m
potential V=240 V
coulombs constant k=9×10⁹Nm²/C²
To find
(a) charge q
(b) charge density σ
Solution
For (a) charge q
As

For (b) charge density
As charge density σ is given as:
σ=q/(4πR²)
σ=(5.333×10⁻⁹) / (4π×(0.20)²)
σ=10.62 nC/m²
 
        
             
        
        
        
Given : A ball of mass 40 g moving at a velocity of 4 m/s.
To find : Calculate the kinetic energy in joules ?
Solution :
The kinetic energy formula is given by,
where, v is the velocity v=4 m/s
m is the mass m=40 g
Convert g into kg,
Substitute the values,
Therefore, the kinetic energy is 0.32 Joules.