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3 years ago

What percentage of the earth's surface is covered in water

Physics

2 answers:

Alla [95]3 years ago

8 0

Answer:

71 % of the earth's surface is covered in water

Novosadov [1.4K]3 years ago

4 0

Answer:

71%

Explanation:

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An 4.0-kg fish pulled upward by a fisherman rises 1.9 m in 2.4 s, starting

mina [271]

Answer:

2.64N

Explanation:

Force = mass * acceleration

Given

mass = 4kg

distance = 1.9m

Time t = 2.4s

Get the acceleration using the equation of motion

S = ut + 1/2at²

1.9 = 0 + 1/2a(2.4)²

1.9 = 5.76a/2

1.9 = 2.88a

a = 1.9/2.88

a = 0.66m/s²

Get the magnitude of the force

Force = 4 * 0.66

Force = 2.64N

Hence the net force acting on the fish is 2.64N

5 0

3 years ago

Acid rain is a secondary pollutant.<br>T or F

aniked [119]

True, acid rain is a secondary pollutant

Examples of a secondary pollutant include ozone, which is formed when hydrocarbons and nitrogen oxides combine in the presence of sunlight, which is formed as NO combines with oxygen in the air; and acid rain, which is formed when sulfur dioxide or nitrogen oxides react with water.

4 0

3 years ago

an aircraft is flying at height of 3400m above the ground.if the angle subtended at a ground observation point by the aircraft p

Kamila [148]

Answer: 588.9 m/s

Explanation:

Given that :

θ = 30°

Height, h = 3400m

Time, t = 10 seconds

From trigonometry ;

Tanθ = opposite / hypotenus

Tan 30 = 3400 / x

x tan 30 = 3400

0.5773502x = 3400

x = 3400 / 0.5773502

x = 5888.9727

Recall ;

Speed = Distance / time

Speed = 5888.9727 / 10

Speed = 588.897 m/s

Speed = 588.9 m/s

7 0

3 years ago

The diameter of a baseball is 7.4 cm and its mass is 0.15 kg. a) If a pitcher throws the baseball at a velocity of 44.3 m/s (100

Tema [17]

Answer:

drag force $F_D = 1.5 \ N$

Velocity (V) = 40.169 m/s

Explanation:

The drag force $F_D$ is given by the formula:

$F_D = C_D * \frac{1}{2}* \rho * V^2*A$

where:

$C_D$ = drag coefficient depending on the Reynolds number

Reynolds number Re = $\frac{\rho *V*D}{ \mu}$

Let's Assume that the air is in room temperature at 25 °C ; Then

density of the air $\rho$ = 1.1845 kg/m³

viscosity of fluid or air $\mu$ = 1.844 × 10⁻⁵ kg/ms

diameter of the baseball D = 7.4 cm

Velocity V = 44.3 m/s

Replacing them into the equation of Reynolds number ; we have :

$Re = \frac{1.1845 \ kg/m^3*44.3 m/s*0.074 m}{1.844*10^{-5}kg/ms}\\\\Re = 2.1*10^5$

A = Projected Area

From the diagram attached below which is gotten from NASA for baseball;

the drag coefficient which depends on Reynolds number is read as:

$C_D$ = 0.3

Projected Area A = $\frac{\pi D^2}{4}$

A = $\frac{\pi 0.074^2}{4}$

A = 0.0043 m²

Finally, drag force is then calculated as ;

$F_D = C_D * \frac{1}{2}* \rho*V^2*A\\\\F_D = 0.3* \frac{1}{2}*1.1845 \ kg/m^3*(44.3 \ m/s) ^2*0.0043 m^2\\\\F_D = 1.5 \ N$

$- F_D = ma$

since acceleration a = $\frac{dV}{dt}$

Then;

$-F_D = m \frac{dV}{dt}$

Also;

velocity (V) = $\frac{dx}{dt}$

Then;

$- F_D = \frac{md_2x}{dt^2}$

$\frac{d_2x}{dt^2} = \frac {- F_D}{m}$

$F_D = 1.5 \ N\\m = 0.15 \ kg$

Then;

$\frac{d_2x}{dt^2} = \frac {- 1.5 }{0.15}$

$\frac{d_2x}{dt^2} =- 10$

Integrating the above equation ; we have :

$\frac{dx}{dt}= - 10 t + C\\$

when time (t) = 0 ; then $\frac{dx}{dt}= V = 44.3$

44.3 = - 10 × 0 + C

C = 44.3

$\frac{dx}{dt}= V = -10 t + 44.3$

Time (t) =

$\frac{distance }{velocity} \\\\= \frac{18.3 m}{44.3 m/s}\\\\= 0.413 s$

∴ Velocity ; $\frac{dx}{dt}= V = - 10t +44.3$

$\frac{dx}{dt}= V = - 10(0.413 s) +44.3$

Velocity (V) = 40.169 m/s

6 0

3 years ago

WILL MARK BRAINIEST!!!!!! (Fill in the blanks with the possible answers at the bottom)

drek231 [11]

Number 3 I think there was so much going In ckcoc v K o n&+\

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2 years ago