if a girl is standing in front of a smooth surface from which a sound is reflected, the girl may hear

A 750 kg National Geographic Drone is rising vertically up into the atmosphere at constant speed. The lift force pushing it upwa

Debora [2.8K]

Answer:

a. 0

b. 1.103625 MJ

c. Conserved

d. 1.103625/n MJ where n = The number of forces

Explanation:

The mass of the drone, m = 750 kg

The upward lift force = 125% of the weight of the drone

The time it takes the drone to reach a height of 250 m = 25 seconds

a. The mechanical energy = The kinetic energy + Potential energy

Therefore, given that the drone stars motion from the surface and was initially at rest, the mechanical energy at the surface = 0

b. The mechanical energy at height, h = 150 m, ME₁₅₀ = The potential energy gained = m·g·h

Where;

g = The acceleration due to gravity = 9.81 m/s²

∴ ME₁₅₀ = 750 kg × 9.81 m/s² × 150 m = 1103625 J = 1.103625 MJ

c. The mechanical energy is equivalent to the potential energy of the drone at the 150 m height, therefore, it is conserved

d. The work done by the force = The energy gained

Therefore, where there are <em>n</em> number of forces, the work done by each force = 1.103625/n MJ

5 0

3 years ago

Light with a frequency of 7.30 x 1014 hz lies in the violet region of the visible spectrum. What is the wavelength of this frequ

Leona [35]

From the theory we know that:

c = λ / T

f = 1 / T

Where:

c = 3. $10^{8}$ / m (the speed of light)

λ is the wavelengh (in meters)

T is the period (in seconds)

f is the frequency (in Hz)

We were told that:

f = 7.30 . $10^{14}$

And we want to find out the value of λ.

c = λ / T

c = λ . 1/T

Swaping 1/T = f

c = λ . f

λ = c / f

λ = 3 . $10^{8}$ / 7.30 . $10^{14}$

λ = 4.12 $10^{-7}$ m

Response: 4.12 $10^{-7}$ m = 412 nm

:-)

6 0

4 years ago

An electrician must decide between 3 heaters. The wire that she is using is rated 15A maximum, anything beyond that is a fire ha

lutik1710 [3]

Use the formula: $P=IV$ , where P is power (watts), I is current (amperes) and V is potential difference (volts).

For the first heater:
$900W = I_{1}*120V$
$I_{1} = 7.5A$

For the second heater:
$1800W = I_{2}*120V$
$I_{2} = 15A$

For the third heater:
$3000W = I_{3}*240V$
$I_{3} = 12.5A$

6 0

3 years ago

If a force of 32000N exerted pressure of 160N/m² , find the area on which the force acts.

Alex17521 [72]

Answer: 200m^2

Explanation:

160N=32000N/x

x*160N=32000

x=200m^2

4 0

2 years ago

The ________ method is duct sizing that considers the each duct section has the same air velocity.

Gennadij [26K]

The equal velocity approach for duct size assumes that the air velocity in each duct segment is the same.

How fast is the air moving through a duct?

The most common unit of air velocity (distance traveled in a unit of time) is feet per minute (FPM). The amount of air passing past a location in the duct per period of time may be calculated by multiplying the airflow by the area of the duct. The standard unit for volume flow is cubic feet per minute (CFM).

What happens when the size of ducts changes to the airflow?

Result for an image The equal velocity technique for duct size makes the assumption that air velocity is constant across the entire duct system.

The main lesson to be learned from this is that when air goes from a bigger to a narrower duct, its velocity rises. The velocity drops when it transitions from a shorter to a bigger duct. The flow rate or the amount of air passing through the duct in cubic feet per minute is the same in all scenarios.

Learn more about air velocity here:

brainly.com/question/3255148

#SPJ4

5 0

2 years ago