Answer:
False
Explanation:
According to the big bang theory, matter was an infinitely small and very high density point which at one point exploded and expanded in all directions, creating what we know as our Universe, which also includes space and time . This happened about 13.8 billion years ago. Theoretical physicists have managed to reconstruct this chronology of events from 1/100 of a second after the Big Bang. After the explosion, while the Universe expanded, it cooled sufficiently and the first subatomic particles were formed: Electrons, Positrons, Mesons, Barions, Neutrinos, Photons among others. Today more than 90 particles are known. This theory solves many unknowns and is very well received by the scientific community, however there is still much to solve, for example, one of the great unsolved scientific problems in the expanding Universe model is whether the Universe is open or closed.
An attempt to solve this problem is to determine if the average density of matter in the Universe is greater than the critical value in Friedmann's model. The mass of a galaxy can be measured by observing the movement of its stars; multiplying the mass of each galaxy by the number of galaxies, it is seen that the density is only 5 to 10% of the critical value.
Answer:
A. when the mass has a displacement of zero
Explanation:
The velocity of a mass on a spring can be calculated by using the law of conservation of energy. In fact, the total energy of the mass-spring system is equal to the sum of the elastic potential energy (U) of the spring and the kinetic energy (K) of the mass:
where
k is the spring constant
x is the displacement of the mass with respect to the equilibrium position of the spring
m is the mass
v is the velocity of the mass
Since the total energy E must remain constant, we can notice the following:
- When the displacement is zero (x=0), the velocity must be maximum, because U=0 so K is maximum
- When the displacement is maximum, the velocity must be minimum (zero), because U is maximum and K=0
Based on these observations, we can conclude that the velocity of the mass is at its maximum value when the displacement is zero, so the correct option is A.
initial speed of 226000 m/s
acceleration of 4.0 x 1014 m/s2,
speed of 781000 m/s
What is Acceleration?
- Acceleration is a rate of change of velocity with respect to time with respect to direction and speed.
- A point or an object moving in a straight line is accelerated if it speeds up or slows down.
- Acceleration formula can be written as,
a = (v - u ) / t m/s²
As we have to find the time taken, the formula can be altered as,
where, t - time taken to reach a final speed
v - final velocity
u - initial velocity
a - acceleration.
Substituting all the given values,
= 1.3875 × 10⁻⁹ seconds.
So, taken to reach the final speed is found to be 1.3 × 10⁻⁹ 8iH..
Answer:
1.52 nm
Explanation:
Using the De Broglie wavelength equation,
λ = h/p where λ = wavelength associated with electron, h = Planck's constant = 6.63 × 10⁻³⁴ Js and p = momentum of electron = mv where m = mass of electron = 9.1 × 10⁻³¹ kg and v = velocity of electron = 4.8 × 10⁵ m/s
So, λ = h/p
λ = h/mv
substituting the values of the variables into the equation, we have
λ = h/mv
λ = 6.63 × 10⁻³⁴ Js/(9.1 × 10⁻³¹ kg × 4.8 × 10⁵ m/s)
λ = 6.63 × 10⁻³⁴ Js/(43.68 × 10⁻²⁶ kgm/s)
λ = 0.1518 × 10⁻⁸ m
λ = 1.518 × 10⁻⁹ m
λ = 1.518 nm
λ ≅ 1.52 nm
