Answer:
0.67 s
Explanation:
This is a simple harmonic motion (SHM).
The displacement,
, of an SHM is given by

A is the amplitude and
is the angular frequency.
We could use a sine function, in which case we will include a phase angle, to indicate that the oscillation began from a non-equilibrium point. We are using the cosine function for this particular case because the oscillation began from an extreme end, which is one-quarter of a single oscillation, when measured from the equilibrium point. One-quarter of an oscillation corresponds to a phase angle of 90° or
radian.
From trigonometry,
if A and B are complementary.
At
, 


So

At
, 





The period,
, is related to
by

Answer: 
Explanation:
Given
Intensity must be reduced by a factor of 6
Intensity is given by 
Substitute
by 

So, the disk must be rotated by an angle of
.
Answer:
It decreases by a factor of 4
Explanation:
The gravitational force between two masses is given by

where
G is the gravitational constant
m1, m2 are the two masses
r is the separation between the two masses
In this problem, the distance between the masses is doubled, so
r' = 2r
Substituting into the equation, we see that the new force is

So, the force decreases by a factor of 4.
Answer:
23.1 N/C
Explanation:
OP = 3 m , OQ = 4 m

q = - 8 nC, Q = 75 nC
Electric field at P due to the charge Q is

Electric field at P due to the charge q is

According to the diagram, tanθ = 3/4
Resolve the components of E1 along x axis and along y axis.
So, Electric field along X axis, Ex = - E1 Cos θ
Ex = - 27 x 4 / 5 = - 21.6 N/C
Electric field along y axis, Ey = E1 Sinθ - E2
Ey = 27 x 3 /5 - 8 = 8.2 N/C
The resultant electric field at P is given by
