In which of the cases below is friction most helpful?

A.

between a moving box and a ramp

B.

between car tires and a road

C.

between a person and a playground slide

D.

between ice skates and an ice rink

Answer: D, All of the above!

Explanation:

I just helped my daughter with this test and it was correct!! Good luck !!

Hi there!

For an object moving in a circle:

Centripetal force = ∑F = mv²/r

Thus:

56 = mv²/r

Rearrange to solve for velocity:

√(56r/m) = v

√(56 × 21)/650 = 1.345 m/s

Answer:

Explanation:

have a good day

Electrons are transferred from oxygen atoms to iron atoms is a redox reaction. Option B is correct.

A redox reaction is a type of chemical reaction in which two species exchange electrons.

Any chemical process in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron is known as an oxidation-reduction reaction.

A redox reaction can result in the creation of hydrogen fluoride. The creation of hydrogen fluoride is another example of a redox reaction.

We can evaluate the oxidation and reduction of reactants by breaking down the process. Each hydrogen turns positive after being oxidized and losing two electrons.

Electrons are transferred from oxygen atoms to iron atoms is a redox reaction.

Hence, the option B is correct.

To learn more about the redox reaction, refer to the blink;

https://brainly.com/question/13293425

#SPJ2

Answer: D) Electrons are transferred from iron atoms to oxygen atoms

If anyone else needs it

Explanation: the iron is increasing in oxidation number (losing electrons) and oxygen is decreasing in oxidation number (gaining electrons). This tells us that we have oxidation (or rusting) taking place.

The magnitude of the magnetic field in the coil is 21.65 T.

The given parameters;

The induced emf in the coil is determined by applying Faradays law;

[tex]emf =N \frac{d\phi }{dt} \\\\emf = N ( \frac{\phi _2 - \phi_1}{t} )\\\\emf= N(\frac{BAsin\ 60 - BAsin\ 90}{t} )\\\\emf = NBA(\frac{sin60 - sn90}{t} )\\\\-0.058 = 500(6\times 10^{-4})\times B\times (\frac{0.866 - 1}{15} )\\\\-0.058 = -0.00268B\\\\B = \frac{0.058}{0.00268} \\\\B = 21.65 \ T[/tex]

Thus, the magnitude of the magnetic field in the coil is 21.65 T.

Learn more here:https://brainly.com/question/13369951

Answer: When a gas is in a smaller volume, the molecules are more confined and bump into the walls of the flask more, thereby exerting a greater pressure.

Explanation:

Answer:

I think c

Explanation:

have a good day/night/ whatever

Fuller pillows that keep her neck straight. The correct option is A.

Thus, Broader pillows that properly support her neck and head would be a better choice. Better sleeping posture and a lower incidence of neck and back pain can both be encouraged by pillows that keep the neck and spine in their natural alignment.

Flat pillows could not offer enough support, which could result in poor alignment and long-term discomfort or suffering.

Stacking pillows in Option B may provide some elevation, but it might not necessarily provide the essential neck and spine support. Option C (without using pillows) can fail to give the head and neck the necessary support and cushioning.

Thus, Fuller pillows that keep her neck straight. The correct option is A.

Learn more about Pillow, refer to the link:

https://brainly.com/question/33757779

#SPJ3

Answer:

R = V/I

Explanation:

Example:

V = IR

R = V/I

If we were to use V = 120 and I = 0.25

R = 120/0.25

R = 480 Ohms

Your resistence would equal Ohms

[tex]▪▪▪▪▪▪▪▪▪▪▪▪▪  {\huge\mathfrak{Answer}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪[/tex]

Let's consider the given terms ~

(Acceleration is negative bbecause train slows down)

(final velocity is 0, because train stops)

Now, let's find the time taken (t) by using the first equation of motion ~

The train will take 10 secs to stop,

Now, let's find how much distance (s) it will cover before it stops using second equation of motion ~

It will cover 500 meters before coming to rest ~

Cuando el niño hace girar 0.7 vueltas por segundo una pelota de hule que se encuentra sujeta mediante un cordón de 0.75 m de longitud, tenemos que:

a) El periodo de la pelota es 1.43 segundos.

b) La velocidad lineal de la pelota es 3.3 m/s.

a) El periodo de la pelota está dado por:

[tex] T = \frac{2\pi}{\omega} [/tex]

En donde:

ω: es la velocidad angular

Dado que la pelota da 0.7 vueltas (revoluciones) cada segundo, la velocidad angular es:

[tex] \omega = \frac{0.7 \:rev}{s}*\frac{2\pi rad}{1 \:rev} = 4.40 rad/s [/tex]

Entonces, el periodo es:

[tex]T = \frac{2\pi}{\omega} = \frac{2\pi}{4.40 rad/s} = 1.43 s[/tex]

b) La velocidad lineal de la pelota se puede calcular usando la siguiente ecuación:

[tex] v = \omega r [/tex]

En donde:

r: es el radio de la circunferencia = longitud del cordón = 0.75 m

[tex]v = \omega r =4.40 rad/s*0.75 m = 3.3 m/s[/tex]

Por lo tanto, la velocidad lineal de la pelota es 3.3 m/s.

Puedes encontar mas aquí:

Espero que te sea de utilidad!

Water waves shake energy over the surface of the sea, while sound waves thump energy through the body of the air. Sound waves are compression waves. They're also called longitudinal waves because the air vibrates along the same direction as the wave travels.

Answer:

[tex]\displaystyle v = 12.4134 \ m/s[/tex]

General Formulas and Concepts:

Energy

Kinetic Energy Formula: [tex]\displaystyle KE = \frac{1}{2}mv^2[/tex]

Explanation:

Step 1: Define

Identify variables.

KE = 7250 J

m= 94.1 kg

Step 2: Solve for v

Topic: AP Physics 1 - Algebra Based

Unit: Energy

Answer: be cut in half

Explanation:

Answer:

It should be mentioned that an efficient way to work this vector addition problem is with the cosine law for general triangles (and since  

a

,

b

 and  

r

 from an isosecles triangle, the angles are easy to figure). However, in the interest of reinforcing the usual systematic approach to vector addition, we note that the angle  

b

 makes with the +x axis  is 30

0

+105

0

=135

0

(a) The x component of  

r

x

​

​

=(10.0m)cos30

0

+(10.0m)cos135

0

=1.59m

(b)  the y component of  

r

 is r

y

​

=(10.0m)sin135

0

 = 12.1 m.

(c) the magnitude of  

r

 is r =  ∣

r

∣=

(1.59m)

2

+(12.1m)

2

​

=12.2m

(d) The angle between  

r

 and the +x direction is tan

−1

[(12.1m)/(1.59m)]=82.5

0

Explanation:

Answer:

1

Explanation:

because when we use v=u+at we derived v-u÷t

Hi there!

We can first find the angular displacement of the first 20 seconds by finding the angular acceleration.

Begin by converting 120 rev/min to rev/sec:

120 rev/min × 1 min/60 sec = 2 rev/sec

ω = αt

2 = 20α

α = 0.1 rev/sec²

θ = ωit + 1/2αt²

The fan starts from rest, so:

θ = 1/2αt²

θ = 1/2(0.1)(20²) = 20 revolutions

Now, for the next 40 seconds, we can find the fan's deceleration:

ωf = ωi + αt

0 = 2 + αt

-2 = 40α

α = -0.05 rad/sec²

Use the above equation:

θ = ωit + 1/2αt²

θ = 2(40) + 1/2(-0.05)(40²) = 80 - 40 = 40 rev

θ = 4800 - 2400 = 2400 revolutions

Add the two:

θtotal = 20 + 40 = 60 revolutions

hun I wish I can help you but I have the same problem here!! sorry

Answer:

At STP,

1 mole of oxygen occupies 22.4litres.

∴ 0.1 mole of oxygen will occupy = 0.1 × 22.4

= 2.24 litres.

Thus, the volume occupied by 0.1 moles of CO

2

at STP is 2.24 L

Hi there!

[tex]\large\boxed{\text{Friction.}}[/tex]

We can go through each:

1) Inertia is NOT a force. Inertia is defined as an object's resistance to motion, or its mass.

2) Friction IS a force because it results in acceleration.

3) Acceleration is not a force, but rather a product of force.

4) Velocity is simply a quantity that can be changed as a result of a force.

Answer:

[tex]315meters[/tex]

Explanation:

Solution is attached.

When a single star with a mass equal to the sun dies, it will become a: white dwarf.

A star is a giant celestial (astronomical) object which comprises a luminous sphere of plasma bounded together by its own gravitational force.

A single star can be defined as a type of star that moves through space alone.

Generally, a star is mainly composed of two (2) hot gases and these are:

I. Hydrogen (H).

II. Helium (He).

Based on Astronomy, when a star runs out of hydrogen, depending on its mass, it would either turn into any of the following:

Similarly, when a single star with a mass equal to the sun dies, it will turn into a white dwarf.

Read more: https://brainly.com/question/17934476

Answer:

Answer → Distance is 5 × 10⁴ km

Explanation:

Gravitational formular

[tex]{ \tt{F = \frac{GMm}{ {r}^{2} } }} \\ [/tex]

For the first case;

[tex]{ \tt{F _{1} = \frac{GMm}{2.5 \times {10}^{4} } }} \\ [/tex]

For the second case;

[tex]{ \tt{F _{2} = \frac{GMm}{r _{2}} }} \\ [/tex]

but F2 = ½F1

Therefore, F1 = 2F2

Hence:

[tex]{ \tt{ \frac{GMm}{2.5 \times {10}^{4} } =2 \times \frac{GMm}{r _{2} } }} \\ \\ { \tt{ \frac{1}{2.5 \times {10}^{4} } = \frac{2}{r _{2} } }} \\ \\ { \tt{r _{2} = 2 \times 2.5 \times {10}^{4} }} \\ \\ { \underline{ \tt{ \: \: r _{2} = 5 \times {10}^{4} \: km \: \: }}}[/tex]

Answer: Distance is 5 × 10⁴ km

Explanation:

Answer: earthquakes and volcanoes

Explanation:

Answer:

Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, radio and television broadcasting.

Answer:

a)object is in uniform motion

Explanation:

velocity is constant.and a=0

body is in uniform motion.

BRAINLIST PLS

Answer:

B

Explanation:

Moment = force * perpendicular distance

Since the beam is balanced(equilibrium), the 2 moments will be equal.

30 * P = 70 * Q

The 2 combinations which achieve this equality is P = 21 and Q = 9

Answer: HP = Horse Power.

Explanation: it is the unit given to tell the motor's particular power and 1hp = 746 watts.

Explanation:

a.displacement is vector quantity there fore

we combine the two direction

[tex] {c}^{2} = \sqrt{ {a}^{2} + {b}^{2} } [/tex]

[tex] {c}^{2 } = \sqrt{ {12}^{2} + {16}^{2} } [/tex]

[tex] {c}^{2} = \sqrt{400 } [/tex]

[tex]c = 20[/tex]

displacement is 20km to wards north

b:average speed

[tex]v = s \div t[/tex]

20/3=6.67

c: please type correctly

Answer:

cuz model clay float

Explanation:

yeah

Hi there!

The equation for the kinetic friction force is:

[tex]F_{kf} = \mu mg[/tex]

We can begin by doing a summation of forces acting on the couch where a positive force is in the direction of the couch's acceleration, or in the direction of the push.

Thus:

[tex]\Sigma F = F_A - F_{kf}[/tex]

Now, plug in the values:

[tex]F_{net}= 650 - (.81 * 9.8 * 71) = \boxed{86.4 N}[/tex]