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A 270,000 kg rocket in gravity -free space expels 270 kg of fuel by exerting a force of 360 N on it. Find the magnitude of the a

Brut [27]

F = m a
360 = 270 x a
1.3 = a

4 0

2 years ago

The Balmer series in hydrogen atom produces only infrared emission. O True O False

lorasvet [3.4K]

Answer:

False

Explanation:

As we know that, the Balmer series gives the n values as,

$n_{i}=2$ .

$[tex]n_{f}=3,4,5,.....\infty$ .

Now the value of wavelength can be calculated as,

$\frac{1}{\lambda}=R(\frac{1}{n_{i} }-\frac{1}{n_{f} } )z^{2}$ .

Here, $R=109677 cm^{-1}$ .

And $n_{f}=3$ .

Now,

$\frac{1}{\lambda}=109677 cm^{-1}(\frac{1}{2}-\frac{1}{3})$ .

Therefore,

$\lambda=\frac{6}{109677} cm\\\lambda=547\times 10^{-9} m\\ \lambda=547 nm$

Therefore, the wavelength of Balmer series lies in visible region which is 547 nm.

8 0

3 years ago

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An object of mass 4kg is moving along a horizontal plane. If the coefficient of kinetic friction is 0.2 find the friction force

lana66690 [7]

Answer:

The friction force acting on the object is 7.84 N

Explanation:

Given;

mass of object, m = 4 kg

coefficient of kinetic friction, μk = 0.2

The friction force acting on the object is calculated as;

F = μkN

F = μkmg

where;

F is the frictional force

m is the mass of the object

g is the acceleration due to gravity

F = 0.2 x 4 x 9.8

F = 7.84 N

Therefore, the friction force acting on the object is 7.84 N

5 0

3 years ago

As part of a safety investigation, two 1900 kg cars traveling at 20 m/s are crashed into different barriers. Part A Find the ave

DedPeter [7]

Answer:

- $29.2\times 10^{3} N$

Explanation:

We are given that

Mass of cars= m=1900 kg

Initial speed of car=u=20 m/s

Final speed of car=v=0

Time= $\Delta t$ =1.3 s

We have to find the average force exerted on the car.

Average force= $\frac{change\;in\;momentum}{\Delta t}$

$F_{avg}=\frac{mv-mu}{1.3}$

$F_{avg}=\frac{1900(0)-1900(20)}{1.3}$

$F_{avg}=\frac{-38000}{1.3}=-29.2\times 10^{3} N$

Hence, the average force exerted on the car that hits a line of water barrels=- $29.2\times 10^{3} N$

8 0

3 years ago

A cup of tea at room temperature of 24°C is heated until it has twice the internal energy. Calculate the final temperature of th

elena-s [515]

The final temperature of the tea cup is 100°C.

<h3>What is internal energy?</h3>

The Internal energy is the energy of a substance due to to the constant random motion of its particles.

The symbol for internal energy of a substance is U and it is measured in Joules.

ΔU = q + W

q is the heat, q = mcΔT

W is the mechanical work.

In conclusion, the final temperature of the tea cup at room temperature of 24 °C which is heated until it has twice the internal energy is 100°C.

Learn more about internal energy at: brainly.com/question/24028630

#SPJ1

3 0

2 years ago