Answer:
r = 5.94 10⁻² m
Explanation:
The magnetic force is given by the ratio
F =q v x B
The bold indicate vectors and the vector product determines that the force is perpendicular to the other two vectors, so the modulus of the velocity does not change, but its direction, therefore the acceleration in Newton's second law is centripetal
F = m a
The magnitude of the force is
F = q v B sin θ
The centripetal acceleration is
a = v² / r
Let's replace
q v B sin θ = m v² / r
r = m v / (q B sin θ)
Let's calculate
r = 9.11 10⁻³¹ 4.8 10⁶ / (1.60 10⁻¹⁹ 9.2 10⁻⁴ sin 30)
r = 5.94 10⁻² m
Answer:
94 kg or 921.6 N
Explanation:
The velocity function is
. The acceleration function, a(t), is the time derivative of the velocity function.

At
,

Because the elevator is going upwards, the net acceleration,
where g us acceleration of gravity.

The resultant weight is

Since the bathroom scale is graduated in kg, it's reading is

The correct answer is
b. low frequencies and low energy.
In fact, microwaves and radio waves have frequency up to
, which are really low compared, for instance, to the frequency of gamma rays (
). Moreover, the energy of an electromagnetic wave is directly proportional to its frequency:

where h is the Planck constant and f the frequency; therefore, low frequency means also low energy.
A pulley ,it the same concept is used to raise an elevator
Vf=vi+at
Vf= (50m/s)+ (5m/s2)(3s)
Vf=65m/s