Complete Question:
Metal sphere A has a charge of − Q . −Q. An identical metal sphere B has a charge of + 2 Q . +2Q. The magnitude of the electric force on sphere B due to sphere A is F . F. The magnitude of the electric force on sphere A due to sphere B must be:
A. 2F
B. F/4
C. F/2
D. F
E. 4F
Answer:
D.
Explanation:
If both spheres can be treated as point charges, they must obey the Coulomb's law, that can be written as follows (in magnitude):

As it can be seen, this force is proportional to the product of the charges, so it must be the same for both charges.
As this force obeys also the Newton's 3rd Law, we conclude that the magnitude of the electric force on sphere A due to sphere B, must be equal to the the magnitude of the force on the sphere B due to the sphere A, i.e., just F.
The answer to this question is False
Answer:
d= 100m
Explanation:
Cheetah kinematic
The cheetah moves with uniformly accelerated movement, and the formulas that describe this movement are:
d= v₀*t + (1/2)*a*t² Formula (1)
vf²=v₀²+2*a*d Formula (2)
vf=v₀+a*t Formula (3)
Where:
d:distance in meters (m)
v₀: initial speed in m/s
vf: final speed in m/s
a: acceleration in m/s²
t: time in seconds (s)
Known Data
v₀ =0
a = 4.5 m/s²
vf= 30 m/s.
Problem development
We apply the formula (2) that has known data to calculate the distance :
vf²=v₀²+2*a*d
(30)²= 0 + 2* 4.5* d

d= 100m