Answer: False
Explanation:
Relative to the concept of radiations, a black body is an object capable of absorbing any form of electromagnetic radiation irrespective of its frequency or angle of incidence when incident on such object.
However, the same cannot be said about real bodies as real bodies are those which reflect all rays incident on them completely and uniformly in all directions.
One very important characteristic of black bodies is that they are ideal emmiters.
The concept of emmisivity is brought about by the existence of real bodies .
This is due to the fact that they are only able to emit radiation at a fraction of the black body energy levels.
Please note that by convention, the emmisivity of a real body is always less thaan 1.
As such they are not able to emit as much radiation as a black body at the same temperature.
Answer:
K.E₂ = mg(h - 2R)
Explanation:
The diagram of the car at the top of the loop is given below. Considering the initial position of the car and the final position as the top of the loop. We apply law of conservation of energy:
K.E₁ + P.E₁ = K.E₂ + P.E₂
where,
K.E₁ = Initial Kinetic Energy = (1/2)mv² = (1/2)m(0 m/s)² = 0 (car initially at rest)
P.E₁ = Initial Potential Energy = mgh
K.E₂ = Final Kinetic Energy at the top of the loop = ?
P.E₂ = Final Potential Energy = mg(2R) (since, the height at top of loop is 2R)
Therefore,
0 + mgh = K.E₂ + mg(2R)
<u>K.E₂ = mg(h - 2R)</u>
Answer:
a)
, with a magnitude of 
b)
, with a magnitude of 
c)
, with a magnitude of 
Explanation:
We have:

We can calculate each component of the acceleration using its definition 

The rate of change of momentum of the ball is 
So for each coordinate:

And these are equal to the components of the net force since F=ma.
If magnitudes is what is asked:

<em>(N and </em>
<em> are the same unit).</em>
Answer:
They are deflected as Earth’s magnetic field exerts force on them.
Explanation:
(Not for cheating, Just to help)
As solar wind approaches Earth, what happens to the charged electrons?
They are absorbed as Earth’s magnetic field exerts force on them.
They grow stronger as Earth’s magnetic field exerts force on them.
They grow weaker as Earth’s magnetic field exerts force on them.
They are deflected as Earth’s magnetic field exerts force on them.
Answer:600N/m
Explanation: Given ;
Applied force(F) = 180N
Total extension (l) = 30cm =0.30m
Spring constant(K) =?
From Hooke's law
F= kx
therefore k= F/x
k = 180N/0.3m
600N/m