(a)
is the wavelength in air of such a sound wave.
(b)
is the wavelength of this wave in tissue.
<u>Explanation:</u>
Frequency and wavelength can be related by the equation,
Velocity = Wavelength x Frequency

where,
v - velocity of light for all EM (electromagnetic) waves in vacuum
Given:
f - 4.50 MHz = 
a) To find the wavelength in air
We know,
Speed of sound in air = 343 m/s
Apply given frequency and speed of sound in air, we get

b) If the speed of sound in tissue is 1500 m/s, find the wavelength of this wave in tissue
Speed of sound in tissue, v = 1500 m/s

1) Answer D not at all
The car is not experiencing any frictional force so that implies that there is no force acting on the car once it starts motion. So, according law of inertia, the car will continue to move and no other force is required.
Friction force is the resistance force that opposes the motion of any object. It arises due to the contact of surfaces.
2) Answer C none
There is no force on any spaceship moving far from any planet. So, according to law of inertia the spacecraft will continue to move at same speed.
Law of inertia states that any object keeps in the state of motion or rest unless a non zero external force is applied on it.
Answer:

ω = 0.0347 rad/s²
a ≅ 1.07 m/s²
Explanation:
Given that:
mass of the model airplane = 0.741 kg
radius of the wire = 30.9 m
Force = 0.795 N
The torque produced by the net thrust about the center of the circle can be calculated as:

where;
F represent the magnitude of the thrust
r represent the radius of the wire
Since we have our parameters in set, the next thing to do is to replace it into the above formula;
So;


(b)
Find the angular acceleration of the airplane when it is in level flight rad/s²

where;
I = moment of inertia
ω = angular acceleration
The moment of inertia (I) can also be illustrated as:

I = ( 0.741) × (30.9)²
I = 0.741 × 954.81
I = 707.51 Kg.m²

Making angular acceleration the subject of the formula; we have;

ω = 
ω = 0.0347 rad/s²
(c)
Find the linear acceleration of the airplane tangent to its flight path.m/s²
the linear acceleration (a) can be given as:
a = ωr
a = 0.0347 × 30.9
a = 1.07223 m/s²
a ≅ 1.07 m/s²
Answer:
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B.a push or pull(which of the following best describes force)