Answer: Wavelength is related to light and also related to energy. The shorter the wavelengths and the higher the frequency corresponds with greater energy. So the longer the wavelengths and lower the frequency results in lower energy. The energy equation is E = hν.
Answer: An 8 kg book at a height of 3 m has the most gravitational potential energy.
Explanation:
Gravitational potential energy is the product of mass of object, height of object and gravitational field.
So, formula to calculate gravitational potential energy is as follows.
U = mgh
where,
m = mass of object
g = gravitational field = 
h = height of object
(A) m = 5 kg and h = 2m
Therefore, its gravitational potential energy is calculated as follows.

(B) m = 8 kg and h = 2 m
Therefore, its gravitational potential energy is calculated as follows.

(C) m = 8 kg and h = 3 m
Therefore, its gravitational potential energy is calculated as follows.

(D) m = 5 kg and h = 3 m
Therefore, its gravitational potential energy is calculated as follows.

Thus, we can conclude that an 8 kg book at a height of 3 m has the most gravitational potential energy.
The angle of reflection is "60°".
Here we apply the law of the concept of reflection then we get the final answer easily.
The angle of incident = angle of reflection
Then, the Angle of the incident =60°
What is reflection?
- Reflection is the phenomenon of light rays returning to the source after striking an obstruction.
- It resembles the way a ball bounces when we toss it on a hard surface.
- Some of the light rays that strike an item are reflected, some of them travel through it, and the remainder are absorbed by the object.
- The given values are:Light from a monochromatic source,= 560 nm
- The angle of incidence,= 60°
- The surface of fused quartz (n),= 1.56
- When a light ray does exist on a flat surface, the law or idea of reflection should apply since it includes both the reflected and "normal" light rays at the mirror surface.
- According to the above law,Angle of incident = angle of reflection
- Then, Angle of incident =60°.
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There's no such thing as "an unbalanced force".
If all of the forces acting on an object all add up to zero, then we say that
<span>the group </span>of forces is balanced. When that happens, the group of forces
has the same effect on the object as if there were no forces on it at all.
An example:
Two people with exactly equal strength are having a tug-of-war. They pull
with equal force in opposite directions. Each person is sweating and straining,
grunting and groaning, and exerting tremendous force. But their forces add up
to zero, and the rope goes nowhere. The <u>group</u> of forces on the rope is balanced.
On the other hand, if one of the offensive linemen is pulling on one end of
the rope, and one of the cheerleaders is pulling on the other end, then their
forces don't add up to zero, because even though they're opposite, they're
not equal. The <u>group</u> of forces is <u>unbalanced</u>, and the rope moves.
A group of forces is either balanced or unbalanced. A single force isn't.