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3 years ago

What does the quantum mechanical model determine about electrons in atoms

1 answer:

8 0

The quantum mechanical model determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus... The energy of electrons in atoms are said to be quantized.

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A rocket is fired at 100 m/s at an angle of 37, how many seconds did it take to get to the top?

Kobotan [32]

Answer:

6.14 s

Explanation:

The time the rocket takes to reach the top is only determined from its vertical motion.

The initial vertical velocity of the rocket is:

$u_y = u sin \theta = (100)(sin 37^{\circ})=60.2 m/s$

where

u = 100 m/s is the initial speed

$\theta=37^{\circ}$ is the angle of launch

Now we can apply the suvat equation for an object in free-fall:

$v_y = u_y +gt$

where

$v_y$ is the vertical velocity at time t

$g=-9.8 m/s^2$ is the acceleration of gravity

The rocket reaches the top when

$v_y =0$

So by substituting into the equation, we find the time t at which this happens:

$t=-\frac{u_y}{g}=-\frac{60.2}{-9.8}=6.14 s$

7 0

4 years ago

a train car of mass 444 kg moving at 5 m/s bounces into another car on the same tracks of mass 344 king. of the second car was m

Kamila [148]

Answer:

3.7 m/s

Explanation:

M = 444 kg

U = 5 m/s

m = 344 kg

u = - 5 m/s

Let the velocity of train is V and the car s v after the collision.

As the collision is elastic

By use of conservation of momentum

MU + mu = MV + mv

444 x 5 - 344 x 5 = 444 V + 344 v

500 = 444 V + 344 v

125 = 111 V + 86 v .... (1)

By using the formula of coefficient of restitution ( e = 1 for elastic collision)

$e = \frac{V-v}{u-U}$

-5 - 5 = V - v

V - v = - 10

v = V + 10

Substitute the value of v in equation (1)

125 = 111 V + 86 (V + 10)

125 = 197 V + 860

197 V = - 735

V = - 3.7 m/s

Thus, the speed of first car after collision is 3.7 m/s. negative sign shows that the direction is reverse as before the collision.

4 0

3 years ago

A:10i - 2j -4k and B: i +7j - k. Determine |A-B|

maksim [4K]

A - B = (10i - 2j - 4k) - (i + 7j - k)

A - B = 9i - 9j - 3k

|A - B| = √(9² + (-9)² + (-3)²) = √189 = 3√19

8 0

3 years ago

A dog is walking back home and its motion is modeled by the graph above. What position was the dog at 3 seconds after it started

hammer [34]

6 meters because 6/3 = 10/5

4 0

3 years ago

Assuming a 8 kilogram bowling ball moving at 2 m/s bounces off a spring at the same speed that had before bouncing what is the a

Naya [18.7K]

a) 32 kg m/s

Assuming the spring is initially at rest, the total momentum of the system before the collision is given only by the momentum of the bowling ball:

$p_i = m u = (8 kg)(2 m/s)=16 kg m/s$

The ball bounces off at the same speed had before, but the new velocity has a negative sign (since the direction is opposite to the initial direction). So, the new momentum of the ball is:

$p_{fB}=m v_b =(8 kg)(-2 m/s)=-16 kg m/s$

The final momentum after the collision is the sum of the momenta of the ball and off the spring:

$p_f = p_{fB}+p_{fS}$

where $p_{fS}$ is the momentum of the spring. For the conservation of momentum,

$p_i = p_f\\p_i = p_{fB}+p_{fS}\\p_{fS}=p_i -p_{fB}=16 kg m/s -(-16 kg m/s)=32 kg m/s$

b) -32 kg m/s

The change in momentum of bowling ball is given by the difference between its final momentum and initial momentum:

$\Delta p=p_{fb}-p_i=-16 kg m/s - 16 kg m/s=-32 kg m/s$

c) 64 N

The change in momentum is equal to the product between the average force and the time of the interaction:

$\Delta p=F \Delta t$

Since we know $\Delta t=0.5 s$ , we can find the magnitude of the force:

$F=\frac{\Delta p}{\Delta t}=\frac{-32 kg m/s}{0.5 s}=-64 N$

The negative sign simply means that the direction of the force is opposite to the initial direction of the ball.

d) The force calculated in the previous step (64 N) is larger than the force of 32 N.

5 0

3 years ago