Answer:
a) t=10.2s
b) The 2g-cube moves first
Explanation:
Since the electric force is the same on both cubes and so is the coefficient of static friction, the first one to move will be the one with less mass.
So, on the 2g-cube the sum of forces are:
Replacing the friction on the first equation:
Thus
The electric force is:
Solving for q:
q=71.44nC
This amount divided by the rate at which they are being charged:
t = 71.44nC / 7nC/s = 10.2s
Answer:
I = 4.75 A
Explanation:
To find the current in the wire you use the following relation:
(1)
E: electric field E(t)=0.0004t2−0.0001t+0.0004
ρ: resistivity of the material = 2.75×10−8 ohm-meters
J: current density
The current density is also given by:
(2)
I: current
A: cross area of the wire = π(d/2)^2
d: diameter of the wire = 0.205 cm = 0.00205 m
You replace the equation (2) into the equation (1), and you solve for the current I:
Next, you replace for all variables:
hence, the current in the wire is 4.75A
Answer:
10.6 meters.
Explanation:
We use the law of conservation of energy, which says that the total energy of the system must remain constant, namely:
In words this means that the initial kinetic energy of the roller coaster plus its gravitational potential energy minus the energy lost due to friction (1700j) must equal to the final kinetic energy at top of the second hill.
Now let us put in the numerical values in the above equation.
and solve for
Notice that this height is greater than the initial height the roller coaster started with because the initial kinetic energy it had.