Answer:
0.0979 N/c
Explanation:
Electric field, E is given as a product of resistivity and current density
E=jP where P is resistivity and j is current density
But the current density is given as
where I is current and A is area and 
Substituting this into the first equation then 
Given diameter of 0.259 cm= 0.00259 m and the radius will be half of it which is 0.001295 m
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I think an education guess for this one because he is thinking about what to guess probably.
Answer: - 7500N
Explanation:
Given the following :
Initial Velocity of car = 108km/hr
Time taken to stop after applying brakes = 4s
Mass of passengers in car = 1000kg
Force exerted by the brakes on the car =?
After 4s, then final Velocity (V) = 0
Initial Velocity (u) of the car = 108km/hr
108km/hr = (108 × 1000)m ÷ (3600)s = 30m/s
Force exerted = mass(m) × acceleration(a)
Acceleration of car = Change in Velocity with time
a = (v - u) / t
a = (0 - 30) / 4
a = - 30/ 4
a = - 7.5m/s^2
Therefore,
Force exerted = mass(m) × acceleration(a)
Force exerted = 1000kg × (-7.5)m/s^2
Force exerted = - 7500N
Answer:
Q = 1.095 x 10^-9 C
Let the force experienced by the top piece of tape be F
F = kQ²/r²
r = distance between the two pieces tape = 1.00cm = 1.00 x 10^ -2 m
1/4(pi)*Eo = k = 8.99 x 10^9 Nm²/C²
The electric force of repulsion between the two charges and the weight of the top piece of tape are equal so
F = kQ²/r² = mg
Where m is the mass of the top piece of tape and g is the acceleration due to gravity
On re-arranging the equation above,
Q² = mgr²/k
Q² = ((11.0 x 10^-6) x 9.8 x (1.00x10^-2)²)/(8.99 x 10^9)
Q = 1.095x10^-9 C
Explanation:
The charge Q on both pieces of tape are equal and both act with a force of repulsion on each other.
The force of repulsion between both tapes pushes the top piece of tape upwards. The weight of the top piece of tape acts vertically downward. Since the top tape is in a position of equilibrium, the two forces acting on the top piece of tape must be equal to each other. This assumption is backed up by newton's first law of motion which states that the summation of all forces acting on a body at rest must be equal to zero. That is
Fe (electric force) - Fg (gravitational force) = 0
Fe = Fg
kQ²/r² = mg
On substituting the respective values for all variables except Q and rearranging the equation Q = 1.09 x 10^-9
