Which of the following scientists won a Nobel Prize for pioneering work in the

A 28 kg student stand on the surface of the Earth. What is the magnitude of the

Contact [7]

Answer:

F = 274.68[N]

Explanation:

The gravitational force is equal to the weight of a body, or this case that of a person. Weight can be calculated by means of the product of mass by gravitational acceleration. In this way we have the following equation:

$F=m*g$

where:

F = force or weight [N]

m = mass = 28 [kg]

g = gravity acceleration = 9.81 [m/s²]

Now replacing:

$F=28*9.81\\F=274.68[N]$

4 0

3 years ago

Un tren emplea cierto tiempo en recorrer 240 km. Si la velocidad hubiera sido 20 km por hora mas que la que llevaba hubiera tard

podryga [215]

Answer:

A train takes some time to travel 240 km. If the speed had been 20 km per hour more than the one it was carrying, it would have taken 2 hours less to travel this distance. In what time did he cover the 240 km

Explanation:

Given that,

A train travelled a distance of 240km

Let the initial speed be

S_1 = x km/hr

Let assume the time spent on the first journey is

t_1 = a

Now if he increase the speed to

S_2 = (x + 20) km/hr

Then, he would have take 2hrs less time

Then, time t_2 = a - 2

The common data fore the two journey is the distance

Speed = distance / time

For the first stage

S_1 = d / t_1

d = S_1 × a

d = x × a

240 = x•a

x = 240 / a Equation 1

For stage two

d = S_2 × t_2

d = (x+20) × (a - 2)

240 = (x+20) × (a - 2). Equation 2

Substitute equation 1 into 2

240 = (240/a + 20) × (a -2)

240 = 240 - 480/a + 20a - 40

240 - 240 + 40 = - 480/a + 20a

240 - 240 + 40 = (-480 + 20a²) / a

40 = (-480 + 20a²) / a

40a = -480 + 20a²

20a² - 40a -480 = 0

Divided through by 20

a² - 2a - 24 = 0

a² + 4a - 6a - 24 = 0

a(a+4) -6(a+4) = 0

(a-6)(a+4) = 0

(a-6) = 0 or (a+4) = 0

So, a = 6 or a = -4

The time cannot be negative, then, the time is a = 6hours

So, t_1 = a = 6hours,

So, the time used in the first journey is 6hours

So, in the second journey the time use is 2hours less than the first journey

Then, t_2 = 6 - 2 = 4 hours

t_1 = 6 hours

t_2 = 4 hours

Spanish

Un tren recorrió una distancia de 240 km.

Deje que la velocidad inicial sea

S_1 = x km / h

Supongamos que el tiempo dedicado al primer viaje es

t_1 = a

Ahora si aumenta la velocidad a

S_2 = (x + 20) km / h

Entonces, habría tomado 2 horas menos de tiempo

Entonces, el tiempo t_2 = a - 2

Los datos comunes para los dos viajes son la distancia.

Velocidad = distancia / tiempo

Para la primera etapa

S_1 = d / t_1

d = S_1 × a

d = x × a

240 = x • a

x = 240 / a Ecuación 1

Para la etapa dos

d = S_2 × t_2

d = (x + 20) × (a - 2)

240 = (x + 20) × (a - 2). Ecuación 2

Sustituye la ecuación 1 en 2

240 = (240 / a + 20) × (a -2)

240 = 240 - 480 / a + 20a - 40

240 - 240 + 40 = - 480 / a + 20a

240 - 240 + 40 = (-480 + 20a²) / a

40 = (-480 + 20a²) / a

40a = -480 + 20a²

20a² - 40a -480 = 0

Dividido entre 20

a² - 2a - 24 = 0

a² + 4a - 6a - 24 = 0

a (a + 4) -6 (a + 4) = 0

(a-6) (a + 4) = 0

(a-6) = 0 o (a + 4) = 0

Entonces, a = 6 o a = -4

El tiempo no puede ser negativo, entonces, el tiempo es a = 6 horas

Entonces, t_1 = a = 6 horas,

Entonces, el tiempo utilizado en el primer viaje es de 6 horas

Entonces, en el segundo viaje, el uso del tiempo es 2 horas menos que el primer viaje

Entonces, t_2 = 6 - 2 = 4 horas

t_1 = 6 horas

t_2 = 4 horas

5 0

3 years ago

By what factor must the amplitude of a sound wave be increased in order to increase the intensity by a factor of 9?a. 9 b. 2 c.

Marta_Voda [28]

Answer:

option D

Explanation:

given,

$intensity\ \alpha \ (Amplitude)^2$

increase the intensity by factor of 9

I₁ = I₀

I₂ = 9 I₀

now,

$\dfrac{I_1}{I_2}=\dfrac{A_1^2}{A_2^2}$

$\dfrac{I_0}{9I_0}=(\dfrac{A_1}{A_2})^2$

$(\dfrac{A_1}{A_2})^2=\dfrac{1}{9}$

$\dfrac{A_1}{A_2}=\dfrac{1}{3}$

A₂ = 3 A₁

hence, amplitude increase with the factor of 3

so, the correct answer is option D

4 0

2 years ago

Read 2 more answers

True or false: Balanced forces can change an object's direction?

slava [35]

The statement is false. Balanced forces can NOT change the speed OR direction of an object's motion. (See Newton's #1 law of motion.)

4 0

2 years ago

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Why is Einstein's description of gravity called a theory, while Newton's is a law?

Ludmilka [50]

Albert Einstein came up with the theory of general relativity to explain the law of gravity, whilst Newton's three laws of gravity is universal. To understand this further, it's best to understand it in scientific terms.

The weird thing about science is that words that are used in a colloquial sense may have a completely opposite definition in scientific terms.

A law in science is a constant and invariable statement that is universal. Wherever you may be in the universe, Newton's three laws of gravity will always be applied.

The word "theory" doesn't imply conjecture or an idea someone made up after a night of drinking. In science, a theory is the highest level of certainty behind mathematical proof -- which isn't even a part of science, obviously. A theory has to be substantiated by all available evidence and contradicted by none. All theories also have to have to be falsifiable. For this reason, theories can never be proven. Einstein's theory of general relativity has great predictive power, but in some cases, the predictions aren't always constant. Theories are often revised to fit new available evidence.

4 0

3 years ago

Read 2 more answers