Sound waves travel in air at 343 m/s. The lowest frequency one can hear is 25.0 Hz; the highest frequency is 25.0 kHz. Find the
1 answer:
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Answer:
I = 1.06886 N s
Explanation:
The expression for momentum is
I = F t = Δp
therefore the momentum is a vector quantity, for which we define a reference system parallel to the floor
Let's find the components of the initial velocity
sin 28.2 = v_y / v
cos 28.2= vₓ / v
v_y = v sin 282
vₓ = v cos 28.2
v_y = 42.8 sin 28.2 = 20.225 m / s
vₓ = 42.8 cos 28.2 = 37.72 m / s
since the ball is heading to the ground, the vertical velocity is negative and the horizontal velocity is positive, it can also be calculated by making
θ = -28.2
v_y = -20.55 m / s
v_x = 37.72 m / s
X axis
Iₓ = Δpₓ =
since the ball moves in the x-axis without changing the velocity, the change in moment must be zero
Δpₓ = m - m v₀ₓ = 0
v_{fx} = v₀ₓ
therefore
Iₓ = 0
Y axis
I_y = Δp_y = p_{fy} -p_{oy}
when the ball reaches the floor its vertical speed is downwards and when it leaves the floor its speed has the same modulus but the direction is upwards
v_{fy} = - v_{oy}
Δp_y = 2 m v_{oy}
Δp_y = 2 0.0260 (20.55)
= 1.0686 N s
the total impulse is
I = Iₓ i ^ + I_y j ^
I = 1.06886 j^ N s
(a) 5.69 N/C, vertically downward
We can calculate the acceleration of the electron by using the SUVAT equation:
where
d = 4.50 m is the distance travelled by the electron
u = 0 is the initial velocity of the electron
is the time of travelling
a is the acceleration
Solving for a,
Given the mass of the electron,
We can find the electric force acting on the electron:
And the electric force can be written as
where
is the charge of the electron
E is the magnitude of the electric field
Solving for E,
The negative sign means that the direction of the electric field is opposite to the direction of the force (because the charge is negative): since the force has same direction of the acceleration (vertically upward), the electric field must point vertically downward.
(b) Yes
We can answer the question by calculating the magnitude of the gravitational force acting on the electron, to check if it is relevant or not. The gravitational force on the electron is:
where
is the mass of the electron
is the acceleration due to gravity
Substituting,
We see that the gravitational force is basically negligible compared to the electric force calculated in part (a), therefore we can say it is justified to ignore the effect of gravity in the problem.
Answer:
A.
B.
Explanation:
The frequency has an inversely proportional relationship with the concept of wavelength, the greater the wavelength, the lower the frequency. For electromagnetic waves, the frequency is equal to the speed of light, divided by the wavelength.
A.
B.