We know the atomic number of Krypton is equal to 36. This method that the Krypton has actually 36 protons and also 36 electrons.

You are watching: The atomic number of krypton (kr) is 36, and its mass number is 84. how many neutrons does it have?

Therefore, substituting values we have:

# neutron = 84 - 36

# neutrons = 48

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The Krypton has 48 neutrons




A 0,2 kg sphere is whirled at continuous angular velocity in a upright circle in ~ the end of a 1.25m long string. If the best ten
*


starrkingschool.net:

A.accelerating

Explanation:

Acceleration is defined as the ratio in between the readjust in velocity and the time taken because that the velocity to change:

*

We must note that the velocity is a vector - therefore it has both a size (the speed) and a direction.

This way that a non-zero acceleration wake up when:

- the rate changes, or

- the direction changes, or

- both the speed and the direction change

For an item moving at consistent speed in a circle, the direction changes, therefore the thing is accelerating.



(1×10^-5)/(1.6×10^-19)= 6.25×10^13 electrons(ans)Notice that the charge of a round is very larger 보다 charge the electron obviously, so every electron top top the round is do of 1.6×10^-19 charge, so you uncovered how countless of this charges are forced for you to make a charge of 1×10^-5 for Example: your electron has charge 2 ~ above it and the sphere has actually charge 200 ~ above it, then the variety of electrons that make up that charge will be 200/2 = 100 electrons.
A photographer in a helicopter ascending vertically in ~ a consistent rate the accidentally drops a camera the end the window when the he

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The time the takes because that the camera to with the floor is 5 s.

Explanation:

To settle this problem, we will use the complimentary fall cinematic equation.

Since the helicopter ascends with constant speed, the camera falls to the ground just by the result of gravity on it.

The speed at i m sorry the helicopter ascends is not stated in the statement, but according to a similar problem, us will use 12.5

*
.

First, we have to calculate the time and also the maximum elevation at i beg your pardon the camera arrives after leave the helicopter.

To calculation the maximum height to which it arrives, us will usage the formula of vertical shot (since the camera leaves the helicopter through a speed upwards that 12,5

*
).

*
=
*
- 2 * g * h

Where:

*
: last speed at maximum height.

*
: early stage speed as soon as it drops from the helicopter.

g: gravity taken at 9.8

*

h: height reached from 60 m when leaving the helicopter

as

*
=0

0=

*
- 2 *
*
* h

clear h:

h=

*
/ (2 *
*
)

h=7,97 m

Then we should calculate the moment it bring away to reach its maximum height:

*
=
*
- g * t

t: time that takes to arrive from the minute it leaves the helicopter in ~ its maximum height.

as

*
=0

0=12.5

*
- 9.8
*
* t

clearing t

t=12.5

*
/ 9.8
*

t=1.27 s.

Now we can calculate the moment it bring away to fall from the maximum elevation of 67.97 m.

The equation we will use is Y=

*

where:

t: time the takes because that the camera come fall.

Y: height from where the camera falls concerning the ground.

*
: initial rate of the camera at the moment of beginning the fall.

g: acceleration of gravity, approximated at 9.8

*

Step 1: as the helicopter ascends with consistent speed, the initial speed of the camera in ~ the minute of fall is 0.

*
=0

So the first term of our equation is nullified.

Step 2: to calculate the time it takes come fall, we clear "t" the the equation:

Y=

*

Y*2=(g*

*
)

*
=
*

*
=t

Step 3: I change the values through the incognites and get "t".

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t=

*

t=3,73 s

The complete time the takes for the camera to fall from the moment it leaves the helicopter is the sum of the moment it takes to reach the maximum suggest of height and the time it takes to loss to the floor from the height.