Why is the restoring force in Hooke's law a negative value?
2 answers:
Explanation:
Hooke's law :
According to the Hooke's law, The force is the directly proportional to the displacement of the string.
On the other hand,
In a simple harmonic motion, The restoring force is directly proportional to the displacement and acts in the opposite direction to that of displacement.
The restoring force is defined as,
Where,
F = restoring force
k = restoring constant
x = displacement
The negative sign shows the force opposes the string's displacement
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Answer:
62.5 %
Explanation:
Let the initial intensity of unpolarized light is Io.
After first polariser the intensity of light becomes I'.
So,
Now it passes through another polariser. The angle between the first polariser and the second polariser is given by Ф. The intensity is I''.
According to the law of Malus
Here, Ф = 30 degree
The percentage change in the intensity is given by
= 62.5 %
Despite current has a magnitude and a direction, like vectors, it is a scalar because it doesn't obey laws of vector addition. For instance, if we consider a junction of 
in a circuit, and two currents entering this junction, we know that the resultant current is just the algebraic sum of the two currents, not the vector sum, so it is not a vector quantity.
Answer:
b) N = 560 N, c) fr = 138.56 N, d) μ = 0.247
Explanation:
a) In the attachment we can see the free body diagram of the system
b) Let's write Newton's second law on the y-axis
N + T_y -W = 0
N = W -T_y
let's use trigonometry for tension
sin θ = T_y / T
cos θ = Tₓ / T
T_y = T sin θ
Tₓ = T cos θ
we substitute
N = W - T sin 30
we calculate
N = 640 - 160 sin 30
N = 560 N
c) as the system goes at constant speed the acceleration is zero
X axis
Tₓ - fr = 0
Tₓ = fr
we substitute and calculate
fr = 160 cos 30
fr = 138.56 N
d) the friction force has the formula
fr = μ N
μ = fr / N
we calculate
μ = 138.56 / 560
μ = 0.247
