To solve this problem, we have to use the formula:
E = h f
where E is total energy, h is Plancks constant
6.626x10^-34 J s, f is frequency
f = E / h
f = 3.686 × 10−24 J / (6.626x10^-34 J s)
<span>f = 5.56 x 10^9 Hz</span>
Answer:3.49 m/s
Explanation:
Given
Speed of marble at Bottom 
Diameter of loop 
As Energy is conserved therefore Energy at top is equal to energy at bottom

,where
is the velocity at bottom







Answer:
Option D.
Value cannot be calculated without knowing the speed of the train
Explanation:
The speed of the beam can only be calculated accurately when the speed of the train is put into consideration. Based of the theory of relativity, the observer is on the ground, and the train is moving with the beam of light inside it. This causes a variation in the reference frames when making judgements of the speed of the beam. The speed of the beam will be more accurate if the observer is moving at the same sped of the train, or the train is stationary.
To get the correct answer, we have to subtract the speed of the train from the speed calculated.
A roller coaster is stopped on a track. When the engineer presses a launch button on the coaster, the coaster moves forward. Explain this change in terms of balanced and unbalanced forces.