Answer:
Explanation:
Given
mass of laptop m=2 kg
The velocity of car u=8 m/s
The coefficient of static friction is
The coefficient of kinetic friction is
As the car is moving, so the coefficient of kinetic friction comes into play
deceleration offered by friction
Using the equation of motion
insert the values
Answer: 259.2 KJ
Explanation:
The formula calculate work don in a circuit is given by :-
, where Q is charge and V is the potential difference.
The formula to calculate charge in circuit :-
, where I is current and t is time.
Given : Current :
Potential difference :
Time :
Now,
Then,
Hence, the work done = 259.2 KJ
a) E = 0
b)
Explanation:
a)
We can solve this problem using Gauss theorem: the electric flux through a Gaussian surface of radius r must be equal to the charge contained by the sphere divided by the vacuum permittivity:
where
E is the electric field
q is the charge contained by the Gaussian surface
is the vacuum permittivity
Here we want to find the electric field at a distance of
r = 12 cm = 0.12 m
Here we are between the inner radius and the outer radius of the shell:
However, we notice that the shell is conducting: this means that the charge inside the conductor will distribute over its outer surface.
This means that a Gaussian surface of radius r = 12 cm, which is smaller than the outer radius of the shell, will contain zero net charge:
q = 0
Therefore, the magnitude of the electric field is also zero:
E = 0
b)
Here we want to find the magnitude of the electric field at a distance of
r = 20 cm = 0.20 m
from the centre of the shell.
Outside the outer surface of the shell, the electric field is equivalent to that produced by a single-point charge of same magnitude Q concentrated at the centre of the shell.
Therefore, it is given by:
where in this problem:
is the charge on the shell
is the distance from the centre of the shell
Substituting, we find: