B.Power is the force of work over a certain distance.
C.Power is the rate at which work is accomplished.
D.Power is the energy supplied in a force.
Answer:
After 14 swings, total length = 57.35 feet.
When the child stops swinging, Total length = 60 feet.
Explanation:
The total length of the rope after 14 swings form a geometric progression which is also known as exponential sequence.
The sum of the term in a Geometry progression is
Sₙ = a(1-rⁿ)/1-r.................(1)
Where Sₙ = sum of the nth term, a= first term, n= number of term, r= common ratio.
n=14, a= 12 feet, r=80% = 0.8.
Substituting the values above into equation(1)
S₁₄ = 12(1-0.8¹⁴)/1-0.8
S₁₄= 12(1-0.04398)/1-0.8
S₁₄= 12(0.95602)/0.2
S₁₄ = 11.47/0.2
S₁₄= 57.35 feet
∴ After 14 swings, the total length the rope will swing is = 57.35 feet.
The total length of the rope when the child stop swinging = sum to infinity of the Geometry progression( exponential sequence).
The sum to infinity of an exponential sequence
S = a/1-r
Where a= first term= 12 feet, r= common ratio = 0.8.
∴ S= 12/1-0.8
S= 12/0.2
S = 60 feet
When the boy stops swinging, the total length the rope have swung = 60 feet.
B.) False
Answer:
and
Explanation:
According to Coulomb's law, the magnitude of force between two point object having change and and by a dicstanced is
Where, is the permitivity of free space and
in SI unit.
Before dcollision:
Charges on both the sphere are and , d=20cm=0.2m, and N
So, from equation (i)
After dcollision: Each ephere have same charge, as at the time of collision there was contach and due to this charge get redistributed which made the charge density equal for both the sphere t. So, both have equal amount of charhe as both are identical.
Charges on both the sphere are mean of total charge, i.e
d=20cm=0.2m, and N
So, from equation (i)
As given that the force is repulsive, so both the sphere have the same nature of charge, either positive or negative, so, here take the magnitude of the charge.
The equation (ii) become:
From equation (iii)
So, the magnitude of initial charges on both the sphere are Coulombs and Colombs or .
Considerion the nature of charges too,
and