Answer:
vB = 0.5418 m/s (→)
aB = - (0.3189/L) m/s²
ωcd = (0.2117/L) rad/s
Explanation:
a) Given:
vA = 0.23 m/s (↑) (constant value)
If
tan θ = vA/vB
For the instant when θ = 23° we have
vB = vA/ tan θ
⇒ vB = 0.23 m/s/tan 23°
⇒ vB = 0.5418 m/s (→)
b) If tan θ = vA/vB ⇒ vA = vB*tan θ
⇒ d(vA)/dt = d(vB*tan θ)/dt
⇒ 0 = tan θ*d(vB)/dt + vB*Sec²θ*dθ/dt
Knowing that
aB = d(vB)/dt
ωcd = dθ/dt
we have
⇒ 0 = tan θ*aB + vB*Sec²θ*ωcd
ωcd = - Sin (2θ)*aB/(2*vB)
If
v = ωcd*L
where v = vA*Cos θ ⇒ ωcd = v/L = vA*Cos θ/L
⇒ vA*Cos θ/L = - Sin (2θ)*aB/(2*vB)
⇒ aB = - vA*vB/((Sin θ)*L)
We plug the known values into the equation
aB = - (0.23 m/s)*(0.5418 m/s)/(L*Sin 23°)
⇒ aB = - (0.3189/L) m/s²
Finally we obtain the angular velocity of CD as follows
ωcd = vA*Cos θ/L
⇒ ωcd = 0.23 m/s*Cos 23°/L
⇒ ωcd = (0.2117/L) rad/s
Answer:
The force is
Explanation:
From the question we are told that
The first diameter is
The second diameter is
Generally the first area is
=>
=>
The second area is
For a hydraulic press the pressure at both end must be equal .
Generally pressure is mathematically represented as
=>
=>
=>
Answer:
The electron tends to go to the region of 4. higher electric potential.
Explanation:
When a charged particle is immersed in an electric field, it experiences a force given by
where
q is the charge of the particle
E is the electric field
The direction of the force depends on the sign of the charge. In particular:
- The force and the electric field have the same direction if the charge is positive
- The force and the electric field have opposite directions if the charge is negative
Therefore, an electron (negative charge) moves in the direction opposite to the electric field lines.
However, electric field lines go from points at higher potential to points at lower potential: so, electrons move from regions at lower potential to regions of higher potential.
Therefore, the correct answer is
The electron tends to go to the region of 4. higher electric potential.
A) A. 380 kHz
To clerly see the image of the fetus, the wavelength of the ultrasound must be 1/4 of the size of the fetus, therefore
The frequency of a wave is given by
where
v is the speed of the wave
is the wavelength
For the ultrasound wave in this problem, we have
v = 1500 m/s is the wave speed
is the wavelength
So, the frequency is
B) B. f(c+v)/c−v
The formula for the Doppler effect is:
where
f' is the apparent frequency
v is the speed of the wave
is the velocity of the receiver (positive if the receiver is moving towards the source, negative if it is moving away from the source)
is the speed of the source (positive if the source is moving away from the receiver, negative if it is moving towards the receiver)
f is the original frequency
In this problem, we have two situations:
- at first, the ultrasound waves reach the blood cells (the receiver) which are moving towards the source with speed
(positive)
- then, the reflected waves is "emitted" by the blood cells (the source) which are moving towards the source with speed
also
v = c = speed of sound in the blood
So the formula becomes
C. A. The gel has a density similar to that of skin, so very little of the incident ultrasonic wave is lost by reflection
The reflection coefficient is
where Z1 and Z2 are the acoustic impedances of the two mediums, and R represents the fraction of the wave that is reflected back. The acoustic impedance Z is directly proportional to the density of the medium, .
In order for the ultrasound to pass through the skin, Z1 and Z2 must be as close as possible: therefore, a gel with density similar to that of skin is applied, in order to make the two acoustic impedances Z1 and Z2 as close as possible, so that R becomes close to zero.
Answer:
T = 0.96 seconds
Explanation:
Given that,
The speed of wave, v = 2.6 m/s
The distance between wave crests,
We need to find the period of the wave motion. Let T be the period. So,
So, the period of the wave motion is equal to 0.96 seconds.