please help me with this I really need help​

Assuming the applied force is exerted parallel to the floor, by Newton's second law both the net vertical and net horizontal forces would be zero:

∑ F (horizontal) = p - f = 0 … … … because the desk is pushed at a constant speed

∑ F (vertical) = n - mg = 0 … … … because the desk doesn't move up or down

where p is the magnitude of the applied force, f is the mag. of kinetic friction, n is the mag. of the normal force due to contact between the floor and desk, and mg is the weight of the desk. We have

n = mg = (100 kg) g = 980 N

and the mag. of friction is proportional to n according to

f = 0.4 n = 392 N

Then the applied force p has magnitude

p = f = 392 N

Answer:

Resistance is defined as the property of a conductor to resist the flow of charges through it. The resistance of conductor is numerically given as the ratio of potential difference across its length to the current flowing through it.

Explanation:

Answer:

D. Meters/Seconds

Explanation:

The time period of a wave is measured in seconds.

A typical wave involves both time and distance.  Consider a sound wave, which is basically a periodic modulation of the local air pressure.  We "hear" the sound because our ears respond to the variations of pressure.

The most common metric of a sound wave is frequency.  This is the rate at which the change in pressure occurs, and is measured in cycles per second, formally known as "hertz".  The period is the inverse of frequency andl has the units of seconds per cycle, commonly stated simply as seconds.

Explanation:

1ml = 2.7g

Xml = 1.5g

Divide 1.5 by 2.7 to find X.

Obviously, since 1.5 is less than 2.7, you know the answer will be less than 1.

(it’s .5555555555)

Answer:

displacement=specific distance

*Velocity=∆displacement/time

*acceleration=∆velocity/time

The Weight of an object is more at pole and less at equator of the earth because the distance of the pole is less than the distance of the equator from the centre of the earth.

Answer:

electric current is derived unit.

Explanation:

According to the definition of electric current, it appears to be a derived quantity. Charge on the other hand seems more fundamental than electric current.

Answer:

nước sôi: 440/17 l

nước 15°C:1260/17 l

Answer:

A simple siphon raises water over a crest and discharges it at a lower level.It works coninueasly due to pull of gravity.

Explanation:

Siphons are tubes which draw fluid over the rim of a tank to a lower point. After an initial pressure change to initiate the flow, siphons operate continuously due to the pull of gravity.

Working:

A simple siphon raises water over a crest and discharges it at a lower level. As water flows through a siphon, energy due to pressure and elevation is either lost to pipe friction or converted to velocity energy.

Answer:

C. Positively charged

Explanation:

The plum pudding model of the atom proposes by J. J. Thomson consisted of electrons which lay embedded as the raisins within a dough or soup that was positively charged. The electron was discovered by J. J. Thomson in 1897 through cathode ray tube experiments.

Based on the plum pudding model, if all the negatively charge electrons contained in an atom are removed, the material remaining will be the positively charged soup

Answer:

The angular velocity after the children jump off is approximately 1.4 rad/s

Explanation:

The given parameters are;

The masses of each child, m₁, and m₂ = 60 kg

The mass of the merry-go-round, m₃ = 140 kg

The initial angular velocity, [tex]\omega_i[/tex] = 0.75 rad/s

The angular velocity after the children jump off = [tex]\omega_f[/tex]  

According to the principle of conservation of angular momentum

The angular momentum = I × ω

The moment of inertia, I = m × R²

The total initial angular momentum = [tex]I_i \times \omega_i = m_i \times R^2 \times \omega_i[/tex]

The total angular momentum after the children jump off = [tex]I_f \times \omega_f = m_f \times R^2 \times \omega_f[/tex]

The initial mass, [tex]m_i[/tex] = m₁ + m₂ + m₃ = 60 kg + 60 kg + 140 kg = 260 kg

The final mass, [tex]m_f[/tex] = m₃ = 140 kg

According to the principle of conservation of linear momentum, we have;

[tex]I_i \times \omega_i[/tex] = [tex]I_f \times \omega_f[/tex]

Therefore;

260 kg × R² × 0.75 rad/s = 140 kg × R² × [tex]\omega_f[/tex]

∴ [tex]\omega _f[/tex] = (260 kg × R² × 0.75 rad/s)/(140 kg × R²) = 1.39285714 rad/s. ≈ 1.4 rad/s

The angular velocity after the children jump off, [tex]\omega _f[/tex] ≈ 1.4 rad/s.

Velocity is directly propertional to dusplacement.Displacement is the shortest dustance between any two points but in a circle dispalcement changes each time as direction is not constant.So, velocity of body in a circular path is variable......

Answer:

3.125J

Explanation:

K.E.= 1/2(mass)(velocity)^2

K.E.=1/2(0.25)(5)^2=3.125

Answer: This phenomenon happens due to upthrust exerted by water.

Explanation:

We know that,

Liquid Pressure is directly proportional to the height of the vertical column in the liquid.(P∝h)

When a bucket filled water is sunk into the water container, there occur difference in the pressure in top and bottom of the water container. Due to this, water exerts an upward force on the bucket filled with water. This is called Uprthrust.

Upthrust on the bucket makes the bucket filled with water lose some of it's weight and causes apparent loss in weight.

Hence, the bucket filled with water seems light while it sinks into water.

To create an electromagnetic field, a magnetic and electric field is involved.

Electromagnetic field consists of both electric and magnetic fields which are produced by human activities through the use of electricity.

With the above definition of electromagnetic field, it's production will involve:

These fields oscillate in perpendicular planes with respect to each other, and are in phase.

Therefore, to create an electromagnetic field, a magnetic and electric field is involved.

Learn more about electromagnetic field here:

https://brainly.com/question/1594186

Answer:

I need this as well

Explanation:

If the poster got the project, please let me know. I'm struggling on this unit and if you don't want to give out the project, help is appreciated too! thanks

Answer:

20m in 2 secs

Explanation:

t=2s

s=20m

hence the maximum height reached by stone is 20m in 2 s

D. The density of the sir increases and the air rises.

When coming in contact with the kettle, it becomes hot, it expands and rises up, due to lesser density as compared to the surrounding air.

Explanation:

If the mass of the inclined plane is large enough, could N ever be equal to mgcosθ. Reasons?

So far I've come up with: mgcosθ−N=ma meaning if N were to equal mgcosθ, ma=0. Since the surfaces are frictionless and since N is acting on the inclined plane too(it'll have a horizontal component), this isn't possible. Am I right? Where am I going wrong?

Answer:

I. Period = 1.3 seconds

II. Frequency = 0.769 Hertz

Explanation:

Given the following data;

Number of oscillation = 240 cycles

Time = 5.2 minutes.

Conversion:

1 minute = 60 seconds

5.2 minutes = X seconds

X = 60 * 5.2

X = 312 seconds

To find the following;

I. Period

Mathematically, the number of oscillation of a pendulum is given by the formula;

[tex] Number \; of \; oscillation = \frac {Time}{Period} [/tex]

Making period the subject of formula, we have;

[tex] Period = \frac {Time}{Number \; of \; oscillation} [/tex]

Substituting into the formula, we have;

[tex] Period = \frac {312}{240} [/tex]

Period = 1.3 seconds

II. Frequency

[tex] Frequency = \frac {1}{Period} [/tex]

Substituting the values into the formula, we have;

[tex] Frequency = \frac {1}{1.3} [/tex]

Frequency = 0.769 Hertz

Answer:

2.5 m

Explanation:

Potential energy is the energy stored in an object as a result of its position relative to other objects

The change in potential energy is given by:

ΔPE = mgh;

where ΔPE is the change in potential energy, m is the mass if the object, g is the acceleration due to gravity and h is the change in height of the object.

Hence given that g = 10 m/s², ΔPE = 150 J, m = 6 kg, hence:

ΔPE = mgh

150 = 6 * 10 * h

150 = 60h

h = 2.5 m

Hence the change in height is 2.5 m

Answer:

which language is this

Explanation:

Answer:

1. The efficiency of the radiator is 90 %

2. The efficiency of the torch is 65 %

3. The efficiency of the car is 40 %

4. The efficiency of the energy saver is 70 %

5. The efficiency of the speaker is 50 %

Explanation:

Efficiency = (Useful energy out ÷ Total energy in) × 100 J

1. Useful energy = 900 J

The total energy in = 1000 J

The efficiency of the radiator = ((900 J)/(1,000 J)) × 100 % = 90 %

2. Useful energy = 65 J

The total energy in = 100 J

The efficiency of the torch = ((65 J)/(100 J)) × 100 % = 65 %

3. Useful energy = 4,000 J

The total energy in = 10,000 J

The efficiency of the car = ((4,000 J)/(10,000 J)) × 100 % = 40 %

4. Useful energy = 700 J

The total energy in = 1,000 J

The efficiency of the energy saver = ((700 J)/(1,000 J)) × 100 % = 70 %

5. Useful energy = 50 J

The total energy in = 100 J

The efficiency of the speaker = ((50 J)/(100 J)) × 100 % = 50 %

Answer:

Explanation:

Force is defined as the push or pull which changes or tries to change the position, state of motion and the shape of the object.

(A) The examples of push are:

To push a chair on the floor, to push the car when it is stopped due to some problem, to push book on the table.

The examples of pull are :

To pull a chair towards you, to pull a string in a game of top, to pull the string in a gym.

(B) To push a chair or a book, the force required is small as compared to the to push a car.

To pull a chair or the string of top is less than the force to pull the string in gym.

Answer:

HOPE IT HELP YOU A LOT :)

I prove it also .

Answer:

Newtons Second law of motion states that"The rate of change of momentum is directly proportional to the force applied"

Answer:

Explanation:

There is no pressure of your feet on the scales, and no pressure of the floor on the scales, so the scales will read zero*. Hence, your weight, in a freely falling lift is zero

Answer:

The acceleration will decrease/reduce

Explanation:

Newton in his second law of motion states that the acceleration of an object is dependent on the force and mass applied on the object. Using the equation as follows:

F = m × a

Where;

F = force (N)

m = mass (kg)

a = acceleration (m/s²)

Acceleration (a) is directly proportional to the force (F) applied but inversely proportional to the mass (m).

According to this question, a friend drops 50 pounds of dog food into a cart being pushed with speed. This means that the mass/weight of the cart was increased. Since the acceleration is inversely proportional to the mass of an object, this means that the acceleration of the cart will DECREASE/REDUCE as the mass increases.

Answer:

658.2 nm

Explanation:

Since the galaxy is moving at relavitistic speed, we use the equation for relativistic Doppler shift of light.

So, the wavelength of light observed on the Earth is λ

λ = λ'([tex]\sqrt{\frac{ 1 + \frac{v}{c} }{1 - \frac{v}{c} } }[/tex])

where  λ' = wavelength of light emitted by galaxy = 656 nm, v = speed of galaxy = 1000 km/s (positive since the galaxy is moving away from the Earth) and c = speed of light = 300000 km/s

So, substituting the values of the variables into the equation, we have

λ = λ'(√[{1 + (v/c)}/(1 - (v/c)]

λ = 656 nm(√[{1 + (1000 km/s/300000 km/s)}/(1 - (1000 km/s/300000 km/s)]

λ = 656 nm(√[{1 + 1/300}/(1 - 1/300]

λ = 656 nm(√[{(300 + 1)/300}/{(300 - 1)/300}]

λ = 656 nm(√[{(301)/300}/{(299)/300}]

λ = 656 nm(√[301/299])

λ = 656 nm(√1.0067)

λ = 656 nm × 1.0033

λ = 658.19 nm

λ ≅ 658.2 nm

So, the wavelength observed on Earth is 658.2 nm

Answer:

I R 2

Explanat

Answer:

A lemon squeezer is a small kitchen utensil designed to extract juice from lemons or other citrus fruit such as oranges, grapefruit, or lime. It is designed to separate and crush the pulp of the fruit in a way that is easy to operate.

Answer:

A lemon squeezer is a small kitchen utensil designed to extract juice from lemons or other citrus fruit such as oranges, grapefruit, or lime. It is designed to separate and crush the pulp of the fruit in a way that is easy to operate.

Explanation:

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