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Elan Coil [88]
3 years ago
7

He is the chemical symbol for which element? Select one: a. hydrogen b. hassium c. helium d. hafnium

Physics
1 answer:
Ludmilka [50]3 years ago
7 0
The answer is C . Helium
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An 3.7 lb hammer head, traveling at 5.8 ft/s strikes a nail and is brought to a stop in 0.00068 s. The acceleration of gravity i
CaHeK987 [17]

Answer:

31677.2 lb

Explanation:

mass of hammer (m) = 3.7 lb

initial velocity (u) = 5.8 ft/s

final velocity (v) = 0

time (t) = 0.00068 s

acceleration due to gravity (g) 32 ft/s^{2}

force = m x ( a + g )

where

  • m is the mass = 3.7 lb
  • g is the acceleration due to gravity = 32 ft/s^{2}
  • a is the acceleration of the hammer

       from v = u + at

       a = (v-u)/ t

       a = (0-5.8)/0.00068 = -8529.4 ( the negative sign showa the its decelerating)

we can substitute all required values into force= m x (a+g)

force = 3.7 x (8529.4 + 32) = 31677.2 lb

       

4 0
2 years ago
Quantum mechanics can be thought of as a ...
Mekhanik [1.2K]

Answer:

c. probablistic view of nature.

Explanation:

According to the problem of particle in a box in one dimension. If the particle energy E is taken less than the height of the barrier V.

Then with the help of classical mechanics it can be prove that the particle can not cross the barrier but according to the quantum mechanics, there is a small but a finite probability to cross the barrier.

Therefore by the above discussion it can be concluded that quantum mechanics can be thought as a probablistic view of nature.

7 0
3 years ago
1. A 700 kg satellite is in orbit 2.4 x 106 meters from the center of the Earth. What is the force of
nevsk [136]

Answer:

4.8 \cdot 10^4 N

Explanation:

The force of gravity acting on the satellite is given by:

F=\frac{GMm}{r^2}

where

G is the gravitational constant

M=5.98\cdot 10^{24} kg is the Earth's mass

m is the mass of the satellite

r is the distance of the satellite from the Earth's centre

Here we have

m = 700 kg

r=2.4\cdot 10^6 m

Substituting into the equation, we find:

F=\frac{(6.67\cdot 10^{-11})(5.98\cdot 10^{24})(700)}{(2.4\cdot 10^6)^2}=4.8 \cdot 10^4 N

<em>Note that the distance mentioned in the problem (2.4 x 10^6 meters) is not realistic, since it is less than the radius of the Earth (6.37 x 10^6 meters).</em>

3 0
3 years ago
How many times longer than the length of one year is the age of the universe?
Len [333]
No one can really tell exactly how old the universe is. However, scientists have attempted to estimate the time by using the concept of Doppler effect which depends on the frequency of the stars and their relative velocities. From literature, the universe is about 13.82 billion years old. Thus, the age of the universe is 13.82×10⁹ times longer than a year.
7 0
3 years ago
Find the wavelength of the balmer series spectral line corresponding to n = 15.
Anna71 [15]

Answer:

371.2 mm

Explanation:

The Balmer series of spectral lines is obtained from the formula

1/λ = R(1/2² -1/n²) where λ = wavelength, R = Rydberg's constant = 1.097 × 10⁷ m⁻¹

when n = 15

1/λ = 1.097 × 10⁷ m⁻¹(1/2² -1/15²)

    = 1.097 × 10⁷ m⁻¹(1/4 -1/225)

    = 1.097 × 10⁷ m⁻¹(0.25 - 0.0044)

    = 1.097 × 10⁷ m⁻¹ 0.245556

    = 2.693 10⁶ m⁻¹

So,

λ  = 1/2.693 10⁶ m⁻¹

    = 0.3712 10⁻⁶ m

    = 371.2 mm

7 0
3 years ago
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