Answer:
The beats frequency measures approximately
4.4 kHz
Explanation:
The beat frequency arises from the original ultrasound frequency, 
, and the frequency of the sound reflected off the car, 
:
(1)
To calculate the frequency of the reflected sound, we apply the Doppler effect formula:
where
v = 340 m/s, the speed of sound
is the velocity of the car
is the frequency of the sound emitted
By substituting values,
Thus, the beat frequency (1) is
F = π/4 ρ d² v²
Explanation:
The formula for force is mass multiplied by acceleration:
F = ma
Acceleration is defined as the change in velocity over the change in time:
F = m Δv / Δt
Since there is no rebound effect, Δv is equal to v.
F = m v / Δt
Mass can be calculated as density multiplied by volume:
F = ρ V v / Δt
Flow rate describes the volume per time:
F = ρ Q v
Flow rate is determined by velocity multiplied by the cross-sectional area:
F = ρ (v A) v
This simplifies to F = ρ A v²
The area of a circle is calculated as pi times the square of the radius, or as pi/4 times the diameter squared:
F = ρ (π/4 d²) v²
Hence, F = π/4 ρ d² v²
Answer:
The direction in which a vehicle accelerates aligns with its velocity direction. However, the force of acceleration works against the car's speed.
Explanation:
The car’s initial acceleration can be found using:
v = v₀ + a t
a = (v-v₀) t
which assumes the initial speed is zero (v₀ = 0 m/s).
a = v / t
a = 300 / t
The acceleration vector matches the direction of the vehicle's movement.
Upon hitting the wall, a force is exerted in the reverse direction to halt the car, thus this acceleration opposes the vehicle’s speed. However, the module should be much greater since the stopping distance is minimal.
The image is absent (but it's not essential to resolve the issue).
The right response is A) decreases, as gravitational force is inversely related to the square of the distance. The magnitude of the gravitational force between two masses M and m, separated by a distance d, is expressed as
where G is the gravitational constant. The formula demonstrates that as the distance d between the two masses increases, the force magnitude diminishes.
