Help please number 8 an 9
1 answer:
8) The reason is that MRIs use radio-waves, which are electromagnetic waves with lower frequency, and so lower energy, than X-rays.
In fact, typical frequencies for radio waves are
, while X-rays have typical frequencies of 
. Since the energy of a wave is given by
where h is the Planck constant and f the frequency, we see that the lower the frequency, the lower the energy. Therefore, radiowaves have less energy than X-rays, so they are less ionising and less dangerous than X-rays.
9) The false statement is:
a) gamma-rays are low-frequency waves.
It's actually the opposite, in fact: gamma rays are the electromagnetic waves with higher frequencies (above
).
In fact, typical frequencies for radio waves are
where h is the Planck constant and f the frequency, we see that the lower the frequency, the lower the energy. Therefore, radiowaves have less energy than X-rays, so they are less ionising and less dangerous than X-rays.
9) The false statement is:
a) gamma-rays are low-frequency waves.
It's actually the opposite, in fact: gamma rays are the electromagnetic waves with higher frequencies (above
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Answer:
The magnitude of the torque is 263.5 N.
Explanation:
Given that,
Applied force = 31 N
Distance from the axis = 8.5 m
She applies her force perpendicularly to a line drawn from the axis of rotation
So, The angle is 90°
We need to calculate the torque
Using formula of torque
Where, F = force
d = distance
Put the value into the formula
Hence, The magnitude of the torque is 263.5 N.
Answer:
Explanation:
v = Velocidad final =
u = Velocidad inicial = 0
t = Tiempo empleado = 15 s
a = Aceleración
De las ecuaciones cinemáticas tenemos
La aceleración del camión en el primer intervalo de tiempo es .