Ask question

Ask question

All categories

3 years ago

7

A boy is going down a slide. As he reaches the bottom, friction causes him to slow down and stop. Which one of Newton's laws is

this?
2nd law
3rd law
1st law
4th law

1 answer:

lara31 [8.8K]3 years ago

8 0

I think it’s the second law

You might be interested in

What is the voltage across a semiconductor bar if the current through it is 0.17 A? The electron concentration in the bar is 2.7

Anastaziya [24]

Answer:

The voltage across a semiconductor bar is 0.068 V.

Explanation:

Given that,

Current = 0.17 A

Electron concentration $n= 2.7\times10^{18}\ cm^{-3}$

Electron mobility $\mu=1000 cm^2/Vs$

Length = 0.1 mm

Area = 500 μm²

We need to calculate the resistivity

Using formula of resistivity

$\sigma=n\times q\times \mu$

$\rho=\dfrac{1}{\sigma}$

Put the value into the formula

$\rho=\dfrac{1}{2.7\times10^{18}\times10^{6}\times1.6\times10^{-19}\times1000\times10^{-4}}$

$\rho=2\ \mu \Omega m$

We need to calculate the resistance

Using formula of resistance

$R=\dfrac{\rho l}{A}$

$R=\dfrac{2\times10^{-6}\times0.1\times10^{-3}}{500\times(10^{-6})^2}$

$R=0.4\ \Omega$

We need to calculate the voltage

Using formula of voltage

$V= IR$

Put the value into the formula

$V=0.17\times0.4$

$V=0.068\ V$

Hence, The voltage across a semiconductor bar is 0.068 V.

6 0

3 years ago

A man of mass 50kg ascends a flight of stairs 5m high in 5 seconds. If acceleration due to gravity is 10ms-2, the power expended

Setler79 [48]

The power expended is 500 W

Explanation:

First of all, we start by calculating the work done by the man in order to ascend: this is equal to the gravitational potential energy gained by the man, which is

$W=mg\Delta h$

where

m = 50 kg is the mass of the man

$g=10 m/s^2$ is the acceleration of gravity

$\Delta h = 5 m$ is the change in height

Substituting,

$W=(50)(10)(5)=2500 J$

Now we can calculate the power expended, which is given by

$P=\frac{W}{t}$

where

W = 2500 J is the work done

t = 5 s is the time elapsed

Substituting, we find

$P=\frac{2500}{5}=500 W$

Learn more about power:

brainly.com/question/7956557

#LearnwithBrainly

7 0

3 years ago

To produce change in motion, a force must be a(n)

Bas_tet [7]

It'd be an unbalanced force

5 0

3 years ago

A transverse wave is traveling through a canal. If the distance between two successive crests is 3.17 m and four crests of the w

Thepotemich [5.8K]

Answer:

a. 0.18Hz

b. 0.56m/s

Explanation:

From the question we can deduct the following parameters

The wavelength, λ is define as the distance between two successful crest or trough and from the question we conclude that wavelength is 3.17m.

Also the period of the wave T can be computed as

T=22.6/4

T=5.65secs.

a. To compute the frequency, recall that frequency, F=1/period.

Hence,

F=1/5.65

F=0.18Hz

b. Next we compute the wave speed.

Wave speed=frequency *wavelength

Wave speed =0.18*3.17

Wave speed =0.56m/s

5 0

3 years ago

An atom of sodium has a larger mass than an atom of neon. How is this possible when neon has so many more valence electrons?

jeka94

The electrons contribute just about zero to the mass of an atom.
It takes more than 1,800 electrons to make the mass of one
proton or neutron.

The naturally occurring element with the most complex atom is
Uranium. That's element #92 , so a neutral uranium atom has
92 electrons. It would take almost exactly 20 times that many
electrons to add the mass of one proton or neutron to the atom!
(And no other element has that many electrons in an atom of it.)

5 0

3 years ago