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8th grade science, one question ​

Answer:

18 newtons

Explanation: I'm taking that class

As the board is raised by an angle θ, the block will be held in place by 3 forces:

• its weight, pointing downward (magnitude w )

• the normal force of the board pushing up on the block, pointing in the direction perpendicular to the board (mag. n)

• static friction, pointing in the direction parallel to the board, opposite the direction the block would slip (mag. f )

Decompose the vectors into components that are parallel and perpendicular to the board (taking the direction of n to be the positive direction perpendicular to the board, and the direction of f to be the negative directoin parallel to it), so that by Newton's second law, we have

• net parallel force:

∑ F = w (//) + f

∑ F = m g sin(θ) - µ n = 0

where µ = 0.45 is the coefficient of static friction, g = 9.80 m/s² is the mag. of the acceleration due to gravity, and m = 15.0 kg is the mass of the block.

• net perpendicular force:

∑ F = n + w (⟂)

∑ F = n - m g cos(θ) = 0

Solve for n in the equation for net perpendicular force:

n = m g cos(θ)

Substitute this into the equation for net parallel force:

m g sin(θ) - 0.45 m g cos(θ) = 0

Solve for θ :

sin(θ) - 0.45 cos(θ) = 0

sin(θ) = 0.45 cos(θ)

tan(θ) = 0.45

θ = tan⁻¹(0.45)

θ ≈ 24.2°

So the maximum angle the board can be lifted before the block starts to slide is about 24.2°, since the coefficient of static friction µ is such that

f = µ n

where f is the maximum magnitude of the static friction force.

Answer:

a = 5 [m/s²]

Explanation:

We must perform a sum of forces on both axes (vertical axis and horizontal axis).

We see that the forces on the vertical axis are the same but in the opposite direction. In this way, there is no movement on the vertical axis y. and we can find the mass of the body.

∑Fy = 0

Fnorm - Fgrav = 0

We know that the force of gravity is equal to the product of mass by gravitational acceleration.

[tex]F_{grav}=m*g[/tex]

where:

m = mass [kg]

g = gravity acceleration = 10 [m/s²]

[tex]100=m*10\\m=100/10\\m=10[kg][/tex]

Since there is only one force on the horizontal axis, this force generates accelerated motion. This force is equal to the product of mass by acceleration, as stipulated by Newton's second law.

∑F = m*a

where:

F = force = 50 [N]

a = acceleration of the body [m/s²]

[tex]F=m*a\\50*10*a\\a=5[m/s^{2} ][/tex]

Answer: because it makes it bigger so scientists would discover more about viruses

Explanation:

Answer:

The average velocity from 1 to 3 seconds is 20 m/s l. X/T = 0 m/1s = zero.

Explanation:

I hope that helped!

Answer: The correct option is D) 14

Explanation:

A transformer is a device used for stepping- up or stepping- down an alternating voltage. It has both primary and secondary windings. Energy is usually supplied through the primary coil and delivered through the secondary coil in a transformer. Using the equation:

Ns= lp

Np= Is

Where Ns--> number of turns in secondary coil

Np--> number of turns in primary coil

Is--> current flow in secondary coil

Ip--> current flow in primary coil.

Therefore Ns= Np Ip/Is

Substituting from the question

Ns= 100×2/14

Ns= 200/14

Ns = 14.28 which is approximately 14 turns in the secondary coil.

Answer:

7.64787 kilograms

Explanation:

75 Newton = 7.64787 Kilograms

hope this helps

pls mark brainliest :D

Answer:

Explanation:

sdfgbaewtfhsertfxzdfhaethsdhdsgfhds

In most cases, the actions of people could be based on distorted feedback.

We know that self perception and self concept is very important. In psychology, it is often very vital to deal with how a person sees himself as this could be the catalyst of the actions of the person. Let us also recall that people do not often act in isolation of the past. This is why some people are said to be the prisoners of the past. They can not just let go of their past failings and mistakes This could have a very bad impact on then future endeavors of such a person.

Let us put this in the context of our discussion. It is common perception that the past of a person could determine the current or future performances of a person. This is common in recruitment exercises.

This implies that when people tend to act, they tend to act based on distorted feedback.

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A circuit that is closed prevents the flow of electrons. So, the correct option is A.

An electrical circuit is defined as an interconnection of electrical components or a model of such interconnection, consisting of electrical elements. An electrical circuit is described as a network consisting of a closed loop, which provides a return path for current.

A closed circuit is required to carry current. When there is a break anywhere in the path, the circuit will open and no current will flow, and the metal atoms in the wire will quickly become cool and electrically neutral.

Thus, a circuit that is closed prevents the flow of electrons. So, the correct option is A.

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An elastic collision is an come across between two bodies wherein the overall kinetic electricity of the two bodies stays the same.

In a super, perfectly elastic collision, there's no internet conversion of kinetic strength into other kinds inclusive of heat, noise, or capacity strength.  An elastic collision is a collision wherein there is no internet loss in kinetic strength within the gadget due to the collision. each momentum and kinetic energy are conserved portions in elastic collisions.

An elastic collision is a collision wherein there is no internet loss in kinetic electricity in the gadget because of the collision.  In the elastic collision, in which the kinetic energy is conserved, the kinetic electricity in an inelastic collision isn't always conserved. In an inelastic collision, the kinetic energy among the colliding bodies is exceptional at the start and the quit of the collision.

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The projectile will travel 6053.13 m in the horizontal direction

The following data were obtained from the question:

The range the projectile will attain can be obtained as follow:

R = u²Sine(2θ) / g

R = 342² × Sine (2×66.3) / 9.8

R = 8785.39 m

Air resistance is 31.1%. Thus, we have

R = 8785.39 - (8785.39 × 31.1%)

R = 8785.39 - 2732.26

R = 6053.13 m

Thus, the projectile will travel 6053.13 m in the horizontal direction

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Answer:

ᏌᎳᏆᎿᏌᎭ ᎭᏆᎳ ᎷᎭᏌ Ꭽ

Explanation:

Answer:

rest

Explanation:

if an object is not in it's position, then we say it is at rest.

Answer:

same for all objects

Explanation:

earth pulls every object by same force of gravity

Answer:

B a current flowing through a coil of wire :)

Explanation:

Explanation:

Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.Touch and hold a clip to pin it. Unpinned clips will be deleted after 1 hour.

Answer:

Light travels as a wave. But unlike sound waves or water waves, it does not need any matter or material to carry its energy along. This means that light can travel through a vacuum—a completely airless space. It speeds through the vacuum of space at 186,400 miles (300,000 km) per second.

Explanation:

Hope this helps :))

Answer:

3.29 s

Explanation:

Using v = u + at where u = initial velocity of boat = 0 m/s since it starts at rest, v = final velocity of boat = 56 m/s, a = acceleration of boat = 17 m/s² and t = time taken to accelerate to 56 m/s.

So, v -= u + at

t = (v - u)/a

substituting the values of the variables, we have

t = (56 m/s - 0 m/s)/17 m/s²

= 56 m/s ÷ 17 m/s²

= 3.29 s

It will take the boat 3.29 s to accelerate to 56 m/s at an acceleration of 17 m/s²

Answer:

8,961

Explanation:

Answer:

D. 160 nm

Explanation:

The energy released from n = 3 to n = 1 must be equal to the sum of energies released from n = 3 to n = 2 and from n = 2 to n = 1. Therefore,

Energy of Photon from 3 to 1 = Energy of Photon from 3 to 2 + Energy of Photon from 2 to 1

[tex]\frac{hc}{\lambda} = \frac{hc}{\lambda_{1}} + \frac{hc}{\lambda_{2}}\\\\\frac{1}{\lambda} = \frac{1}{\lambda_{1}} + \frac{1}{\lambda_{2}}[/tex]

where,

λ = wavelength of photon released from 3 to 1 = ?

λ₁ = wavelength of photon released from 3 to 2 = 800 nm

λ₂ = wavelength of photon released from 2 to 1 = 200 nm

Therefore,

[tex]\frac{1}{\lambda} = \frac{1}{800\ nm} + \frac{1}{200\ nm}\\\\\frac{1}{\lambda} = 0.00625 nm^{-1}\\\\\lambda = \frac{1}{0.00625 nm^{-1}}\\\\\lambda = 160 nm[/tex]

Therefore, the correct option is:

D. 160 nm

Answer:w= 1,750 J

Explanation: w=f x d

w=350 N x 5 m

w= 1,750 J

(pretty sure that’s right)

The work produced by the object to move the car is of 1750 J.

Given data:

The magnitude of force applied on the object is, F = 350 N.

The distance moved by the car is, s = 5 m.

When some magnitude of force is applied on any object to displace it, then the output of the applied force is known as work done. The mathematical expression for the work done is given as,

[tex]W = F \times s[/tex]

Solving as,

[tex]W = 350 \times 5\\\\W = 1750 \;\rm J[/tex]

Thus, we can conclude that the work produced by the object to move the car is of 1750 J.

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Answer:

g = 0.85 m[tex]s^{-2}[/tex]

Explanation:

g = [tex]\frac{GM}{h^{2} }[/tex]

were; g is the acceleration due to Earth's gravity, G is Newton's gravitation constant (6.674 x [tex]10^{-11}[/tex] N[tex]m^{2}[/tex][tex]kg^{-2}[/tex]), M is the mass of the earth (5.972 x [tex]10^{24}[/tex] kg), and h is the distance of meteoroid to the earth.

h = 3.40 x R

  = 3.40 x 6371 km

h = 21661.4 km

  = 21661400 m

Thus,

g = [tex]\frac{6.674*10^{-11}*5.972*10^{24} }{(21661400)^{2} }[/tex]

  = [tex]\frac{3.9857 *10^{14} }{4.6922*10^{14} }[/tex]

  = 0.84944

g = 0.85 m[tex]s^{-2}[/tex]

The acceleration due to the Earth's gravitation is 0.85 m[tex]s^{-2}[/tex].

Answer:

The truck and car have the same momentum.

Explanation:

[tex]m_1[/tex] = Mass of car = [tex]2000\ \text{lb}=2000\times0.45359237\ \text{kg}[/tex]

[tex]v_1[/tex] = Velocity of car = [tex]\dfrac{100}{3.6}\ \text{m/s}[/tex]

[tex]m_2[/tex] = Mass of truck = [tex]4000\times0.45359237\ \text{kg}[/tex]

[tex]v_2[/tex] = Velocity of truck = [tex]\dfrac{50}{3.6}\ \text{m/s}[/tex]

Momentum of car

[tex]p_1=m_1v_1\\\Rightarrow p_1=2000\times0.45359237\times \dfrac{100}{3.6}\\\Rightarrow p_1=25199.58\ \text{kg m/s}[/tex]

Momentum of the truck

[tex]p_2=m_2v_2\\\Rightarrow p_2=4000\times0.45359237\times \dfrac{50}{3.6}\\\Rightarrow p_2=25199.58\ \text{kg m/s}[/tex]

Both the truck and car have the same momentum of [tex]25199.58\ \text{kg m/s}[/tex].

Answer:

velocity

Explanation:

acceleration is defined as the rate of change of velocity

Two vectors are parallel when the angle between them is either 0° (the vectors point in the same direction) or 180° (the vectors point in opposite directions).

In both mathematics and physics, the term "vector" is used informally to describe certain quantities (also known as "scalars") that cannot be described by a single number or by the constituent parts of some vector spaces.

Historically, vectors were introduced in geometry and physics (usually in mechanics) for things like displacements, forces, and velocity that have both a magnitude and a direction. Similar to how lengths, masses, and time are represented by real numbers, these quantities can be thought of as geometric vectors.

Tuples, which are finite sequences of numbers with a definite length, are also referred to as vectors in some settings.

Tuples and geometric vectors may both be added to and scaled, and the idea of a vector space is a result of these vector operations.

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Answer:

See Explanation

Explanation:

Whenever a force is applied in an object in the opposite direction of its motion. It  tends to slow down the speed of the object. Therefore, this force is called the decelerating force and the acceleration produced by it is called deceleration.

The deceleration produced in this case by this decelerating force has a direction opposite to the direction of motion or velocity of the object. Therefore, this deceleration is defined with a negative sign along with its magnitude.

Due to this opposite direction, term negative acceleration is also used instead of deceleration.

Answer: Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Explanation:

Answer:

5.33 km /hr

Explanation:

45 minutes is  3/4   or   .75 hr

4 km / .75 hr = 5 1/3   or  5.33 km/hr

Answer:

Due east - 0.42mps

Due west - 0.29mps

Explanation:

So for the 5 meters 12s

and 2 meters 7s

for the first one we will do 12/5 = 2.4

for the second one 7/2 = 3.5

that is the amount of seconds per meter but we want meters per seconds so

5/12 = 0.42mps

2/7 = 0.29mps

Answer:

t = 1400 s

Explanation:

Given that,

Distance covered, d = 350 km = 350000 m

Speed of the object, v = 25 m/s

We need to find the time it takes to do that. Let the time is t. The formula for the speed of an object is given by :

v = d/t

i.e.

[tex]t=\dfrac{d}{v}[/tex]

Putting all the values,

[tex]t=\dfrac{350000}{25}\\\\=1400\ s[/tex]

So, the time taken by it is 1400 seconds.