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3 years ago

Why does a lead of a pencil becomes smaller after use brainly people plplplsss help

1 answer:

6 0

Pencil lead is made up of graphite. These graphite particles stick to the fiber in the paper when you write. So what happens is it transfers from the pencil to the paper. When you write you're literally rubbing the graphite off the pencil.

I hope this explanation will help you out.

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A 180 meter long train, travelling at a constant speed, is passing a car driving on an adjacent lane at a speed of 72 km/h. Know

Lana71 [14]

Answer:

The velocity of the train is 82.8 km/h

Explanation:

The equation for the position of the train and the car is as follows:

x = x0 + v · t

Where:

x = position at time "t".

x0 = initial position.

v = velocity.

t = time.

First, let´s calculate the distance traveled by the car in 60 s (1/60 h). Let´s place the origin of the frame of reference at the front of the train when it starts to pass the car so that the initial position of the car is 0 (x0 = 0 m):

x = 0 m + 72 km/h · (1/60) h

x = 1.2 km.

Then, if the whole train passes the car at that time, the position of the front of the train at that time will be 1.2 km + 0.18 km = 1.38 km.

Then using the equation of position we can obtain the velocity:

x = x0 + v · t

1.38 km = 0 m + v · (1/60) h

1.38 km / (1/60) h = v

v = 82.8 km/h

The velocity of the train is 82,8 km/h

The same result could be obtained using the rear of the train. You only have to identify where the rear is at t = 0 and where it is at t = 60 s.

Try it!

6 0

3 years ago

What pair of atoms forms ionic bonds

WARRIOR [948]

K,F potassium , fluorine form ionic bond,

8 0

3 years ago

An air-filled capacitor consists of two parallel plates, each with an area of 7.60 cm2, separated by a distance of 1.50 mm. A 25

torisob [31]

Answer:

The electric field is 16666.66 V/m.

The surface charge density is $1.474\times10^{-7}\ C/m^2$

The capacitance is $4.484\times10^{-12}\ F$

The charge on each plate is $112.1\times10^{-12}\ C$

Explanation:

Given that,

Area =7.70 cm²

Distance = 1.50 mm

Potential difference = 25.0 V

Suppose we find the electric field between the plates, the surface charge density, the capacitance and the charge on each plates.

We need to calculate the electric field

Using formula of electric field

$E=\dfrac{V}{d}$

Put the value into the formula

$E=\dfrac{25.0}{1.50\times10^{-3}}$

$E=16666.66\ V/m$

We need to calculate the charge density

Using formula of charge density

$\sigma=E\times\epsilon_{0}$

Put the value into the formula

$\sigma=16666.66\times8.85\times10^{-12}$

$\sigma=1.474\times10^{-7}\ C/m^2$

We need to calculate the capacitance

Using formula of capacitance

$C=\dfrac{\epsilon_{0}A}{d}$

Put the value into the formula

$C=\dfrac{8.85\times10^{-12}\times7.60\times10^{-4}}{1.50\times10^{-3}}$

$C=4.484\times10^{-12}\ F$

We need to calculate the charge

Using formula of charge

$q=CV$

Put the value into the formula

$q=4.484\times10^{-12}\times25.0$

$q=112.1\times10^{-12}\ C$

Hence, The electric field is 16666.66 V/m.

The surface charge density is $1.474\times10^{-7}\ C/m^2$

The capacitance is $4.484\times10^{-12}\ F$

The charge on each plate is $112.1\times10^{-12}\ C$

8 0

3 years ago

what was the mass of a cannkn ball whose velocity is 200m/s if it were shot from 1000kg that recoils a 2m/s. Solve step by step

Whitepunk [10]

The famous Newton’s Third Law states that “For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object.”

By using this,

10grams or 0.01kg of bullet with speed 400 m/sec and 5kg gun recoil with speed suppose ‘v’.

0.01×400=5×v

4/5=v

v=0.8m/sec ANSWER.

6 0

3 years ago

Which two of the following involve the same energy transfer. Assume that the same substance and the same mass is involved in all

Elanso [62]

B. evaporation
c. condensation

They are opposite processes that involve the same transfer of energy

3 0

3 years ago