Pls help i’m in a test and don’t know what to do

Why do different stars have different life cycles

lana66690 [7]

The answer is shape is determined. A stars life cycle is determined in its size

3 0

3 years ago

a stationary police officer directs radio waves emitted by a radar gun at a vehicle toward the officer. Compared to the emitted

Arisa [49]

Answer:

D) Higher Frequency

Explanation:

Higher frequency because it says a vehicle “towards” the officer

3 0

3 years ago

A 52 kg and a 95 kg skydiver jump from an airplane at an altitude of 4750 m, both falling in the pike position. Assume all value

Scilla [17]

Answer: 52 kg skydiver: 9.09 m/s and 522.55 s

95 kg skydiver: 12.3 m/s and 386.2 s

Explanation: Drag Force is an opposite force when an object is moving in a fluid.

For skydivers, when falling through the air, the forces acting on it are gravitational and drag forces. At a certain point, drag force equals gravitational force, which is constant on any part of the planet, producing a net force that is zero. Since there is no net force, there is no acceleration and, consequently, velocity is constant. When that happens, the person reached the Terminal Velocity.

Drag Force and Velocity are proportional to the squared speed. So, terminal velocity is given by:

$F_{G}=F_{D}$

$mg=\frac{1}{2}C \rho Av_{T}^{2}$

$v_{T}=\sqrt{\frac{2mg}{\rho CA} }$

where

m is mass in kg

g is acceleration due to gravitational force in m/s²

ρ is density of the fluid in kg/m³

C is drag coefficient

A is area of the object in the fluid in m²

Calculating:

The 52kg skydiver has terminal velocity of:

$v_{T}=\sqrt{\frac{2(52)(9.8)}{(1.21)(0.7)(0.14)} }$

$v_{T}=$ 9.09

The 95kg skydiver's terminal velocity is

$v_{T}=\sqrt{\frac{2(95)(9.8)}{(1.21)(0.7)(0.14)} }$

$v_{T}=$ 12.3

The 52 kg and 95kg skydivers' terminal velocity are 9.09m/s and 12.3m/s, respectively.

The time each one will reach the floor will be:

52 kg at 9.09 m/s:

$t=\frac{4750}{9.09}$

t = 522.5

95 kg at 12.3 m/s:

$t=\frac{4750}{12.3}$

t = 386.2

The 52 kg and 95kg skydivers' time to reach the floor are 522.5 s and 386.2 s, respectively.

3 0

3 years ago

A satellite in a nearly circular orbit is 2000 km above earth's surface. the radius of earth is approximately 6400 km. if the sa

Ann [662]

Velocity is computed using the formula:

$v= \frac{d}{t}$
Where:
V = speed
d = distance traveled
t = time/period

First you need to consider that the orbit is circular. To get the measurement or the distance going around Earth, you will need to get the circumference of the path.

$C = 2 \pi r$

Where:
C = circumference
π = 3.14
r = radius

The Earth has a radius of 6,400km, but you also need to consider that the satellite is orbiting above the surface of the Earth, so you add in the 2,000km to that radius.

r = 6,400Km + 2,000Km = 8,400Km

Next step is to insert that into our circumference formula:

$C = 2 \pi r$
$C = 2 \pi 8,400Km$
$C = 52,778.76 Km$

The distance traveled would then be 52,778.76Km

Now that we have the distance, we can then get the velocity:

$v= \frac{d}{t}$
$v= \frac{52,778.76Km}{12hrs}$
$v= 4,398.23km/hr$

The speed of the satellite is 4,398.23km/hr.

7 0

3 years ago

2. Two charged particles as shown in figure below. QP = +10 μC and Qq = +20 μC are separated by a distance r = 10 cm. What is th

netineya [11]

Answer:

F = 180 N

Explanation:

Given that,

Charge, q₁ = 10 μC

Charge, q₂ = 20 μC

The distance between the charges, r = 10 cm = 0.1 m

We need to find the magnitude of the electrostatic force. The formula for the electrostatic force is given by :

$F=\dfrac{kq_1q_2}{r^2}\\\\F=\dfrac{9\times 10^9\times 10\times 10^{-6}\times 20\times 10^{-6}}{(0.1)^2}\\F=180\ N$

So, the magnitude of the electrostatic force is 180 N.

4 0

3 years ago