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## At a playground, a child slides down a slide that makes a 42° angle with the horizontal direction. the coefficient of kinetic friction for the child sliding on the slide is 0.20. what is the magnitude of her acceleration during her sliding?

Assuming metric units, metre, kilogram and seconds

Best approach: draw a free body diagram and identify forces acting on the child, which are:
gravity, which can be decomposed into normal and parallel (to slide) components
N=mg(cos(theta)) [pressing on slide surface]
F=mg(sin(theta))  [pushing child downwards, also cause for acceleration]
m=mass of child (in kg)
g=acceleration due to gravity = 9.81 m/s^2
theta=angle with horizontal = 42 degrees

Similarly, kinetic friction is slowing down the child, pushing against F, and equal to
Fr=mu*N=mu*mg(cos(theta))
mu=coefficient of kinetic friction = 0.2

The net force pushing child downwards along slide is therefore
Fnet=F-Fr
=mg(sin(theta))-mu*mg(cos(theta))
=mg(sin(theta)-mu*cos(theta))   [ assuming sin(theta)> mu*cos(theta) ]

From Newton’s second law,
F=ma, or
a=F/m
=mg(sin(theta)-mu*cos(theta))  /  m
= g(sin(theta)-mu*cos(theta))   [ m/s^2]

In case imperial units are used, g is approximately 32.2 feet/s^2.
and the answer will be in the same units [ft/s^2] since sin, cos and mu are pure numbers.

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## How is energy converted in a hydroelectric plant? A) The kinetic energy of water is converted to electrical energy when water flows down the dam's channel and into the transformer. B) The potential energy of water is converted to electrical energy when water flows past a generator. C) The kinetic energy of water turns turbines; the mechanical energy of the turbines turns the generator, which produces electrical energy. D) The potential energy of water turns the generator's turbines, which results in the production of electrical energy.

How is energy converted in a hydroelectric plant? A) The kinetic energy of water is converted to electrical energy when water flows down the dam’s channel and into the transformer. B) The potential energy of water is converted to electrical energy when water flows past a generator. C) The kinetic energy of water turns turbines; the mechanical energy of the turbines turns the generator, which produces electrical energy. D) The potential energy of water turns the generator’s turbines, which results in the production of electrical energy.

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## Why is water an excellent solvent for most ionic compounds and polar covalent molecules but not for non-polar compounds? A) Water is a polar molecule. B) Water has a charge like an ion. C) Water is a deionizing substance. D) Water molecules have an unusually high kinetic energy in the liquid state.

A)Water is a polar molecule. When talking about solubility, the rule that “like dissolves like” is usually correct. This means that polar substances are soluble in other polar substances. This occurs because the opposite partially charged ends of different polar molecules are attracted to each other. Similarly, the partially charged ends of polar molecules will be even more attracted to the charged ends of an ionic compound’s molecule. This is why,for example, table salt/ NaCl, which is an ionic compound, dissolves in water.

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Natural Forces Affecting the Driver:

1. While the car stops, the person continues moving the way that the car were moving and then hits the obstacle in the car or the person can be thrown out of the vehicle. If the person wears belt, he will stop moving with the vehicle and won’t hit the obstacle.

2. We count approximate kinetic energy using the formula K = v^2. So the vehicle which is moving at 30 mph will have four times less kinetic energy than vehicle which is moving at 60 mph. If they have the same road conditions, the breaking distance will be four times as great for the car moving twice as fast.

3. Kinetic energy depends on object’s mass and velocity and it has direct relationship with the stopping distance. The lesser mass of the vehicle = the lesser kinetic energy and lesser stopping distance. => If both vehicles have the same velocity, then small vehicle has lesser kinetic energy than large vehicle.

4. We know that kinetic energy has this relationship with velocity K = v^2. So the best way to prepare to enter sharp curves in the roadway is to lower the speed. The most appropriate speed is 20-30 mph, but it depends on road conditions and car’s breaks condition.

5. Car crashes can happen with everyone so the best way is to be prepared. First the driver should wear a seatbelt while he’s driving. He should check his tires and breaks condition regularly. And also it’s important to slow down the vehicle while entering sharp curves. Without following these rules, the driver can get catastrophic injuries in a car crash.

Signs, Signals, and Pavement Markings:

1. It doesn’t matter where you go. All you need is to learn highway code. It’s very different to know the meanings of every road sign. Also, it’s necessary to check your car’s conditions and you should take some spare parts for your car in case of accidents. So wherever you go, it’s important to be prepared.

2. You should stop before crossing and take few minutes to make sure there is no train approaching. If there is no train approaching, you can pass a railroad crossing. If you see approaching train, you should wait until it will pass a railroad crossing.

3. You should stop before the lights and wait to check the traffic movement and signs. Make sure that everything is safe and pass the intersection. Don’t move fast to avoid accidents.

4. Flashing yellow light means that it’s not necessary to stop but you should to pay attention on the traffic movement. So it would be better to yield before the lights and make sure if it’s safe to move. After that you can cross the intersection.

5. The line change means that the lane changes and you can’t cross solid lines. Pay more attention on road marking because it shows how you should behave on the road or highway.

6. As you approach the next exit and  your passengers need to use the restroom and get some food, you should look for green signs which indicate food and rest stops. You should to slow down if you don’t want to skip the sign.

7. When you take the exit ramp off the expressway and merge onto the next road, you see yellow lines dividing the roadway which indicates that there is oncoming traffic and this is a two-way highway.

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## What is the Celsius temperature of 1 mole of a gas that has an average kinetic energy of 4,265 joules? 69°C 96°C 369°C 435°C

This problem is to apply Roult’s Law.

Roult’s Law states that the vapor pressure, p, of a solution of a non-volatile solute is equal to the vapor pressure of the pure solvent, Po solv, times the mole fraction of the solvent, Xsolv

p = Xsolv * Po sol

X solv = number of moles of solvent / number of moles of solution

The solvent is water and the solute (not volatile) is glycerin.

Number of moles = mass in grams / molar mass

mass of water = 132 ml * 1 g/ml = 132 g

molar mass of water = 18 g/mol

=> number of moles of water = 132 g / 18 g/mol = 7.33333 mol

mass of glycerin = 27.2 g

molar mass of glycerin:, C3H8O3: 3 * 12 g/mol + 8 * 1 g/mol + 3*16 g/mol = 92 g/mol

number of moles of glycerin = 27.2g / 92 g/mol = 0.29565

total number of moles = 7.33333 moles + 0.29565 moles = 7.62898 moles

=> X solv = 7.33333 / 7.62898 = 0.96125

=> p = 0.96125 * 31.8 torr ≈ 30.57 torr ≈ 30.6 torr.

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## The table describes a gas stored in four different containers. properties of stored gas container properties 1 · low number of collisions with container walls · medium average kinetic energy · large number of particles 2 · large number of collisions with container walls · medium average kinetic energy · small number of particles with little spaces between them 3 · large number of collisions with container walls · high average kinetic energy · large number of particles with large spaces between them 4 · few collisions with container walls · low average kinetic energy · small number of particles which container has gas stored at the highest temperature?

The equation for how temperature changes the resistance R is:

R=R₀(1+α(T-T₀)), where R₀ is the resistance at T₀=20°C, T is the temperature for which we want to calculate the resistance and α is the temperature coefficient for resistance.

The resistance of the copper wire increases by 18% or by 0.18, so the new value for the resistance is R=1.18*R₀.

T₀=20°C
=0.0068
R=1.18*R₀

Now we need to input that into the equation for resistance change and solve for temperature T.

1.18R₀=R₀(1+α(T-20)), R₀ cancels out,

1.18=1+α(T-20),

1.18-1=α(T-20), we divide by α,

0.18/α=T-20, we put 20 on the left side,

26.47+20=T

T=46.47°C

So the temperature on which the resistance of copper wire will increase by 18% is T=46.47°C.

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## A 227 kg motorcycle moves with a velocity of 8 m/s. What is its kinetic energy? _______ Joules

The gravitational force Fg between two objects is given by the equation:

Fg=(G*m₁*m₂)/r₂, where G=6.67*10^-11 m³ kg⁻¹ s⁻² is the gravitational constant, m₁ and m₂ are the masses of the two bodies and r is the distance between those bodies.

Due to the gravitational attraction the pencil and the eraser will attract if we there is no friction on the surface.

m₁=10 g=0.01 kg is the mass of the pencil
m₂=20 g=0.02 kg is the mass of the eraser
r=2.5 cm = 0.025 m

First we calculate the Fg:

Fg={(6.67*10^-11)*0.01*0.02}/(0.025²)=2.1344*10^-11 N

To get the velocity v of the pencil:

v²=2as, where a is the acceleration of the pencil and s is the path. In our case s=r so we can write:

v²=2ar

a=Fg/m₁= 2.133*10^-9 m/s²

v²=2*(2.133*10^-9)*0.025=1.0665*10^-10

v=√(1.0665*10^-10)=1.0327*10^-5 m/s

We have the velocity and the acceleration, so we can calculate the time t with the equation:

t=v/a=(1.0327*10^-5)/(2.133*10^-9)=4841.6 s

1 hour has 3600 s so when we divide time t in seconds by 3600 we get time T in hours:

T=t/3600=4841.6/3600=1.3449 h.

So the time for the pencil and eraser to touch is T=1.3449 hours.

Also time T can be expressed like T= 1h and 20 mins and 41.64 s

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## What is the average kinetic energy of 1 mole of a gas at -32 degrees Celsius? (R = 8.314 J/K-mol) 3.006 x 103 J -3.997 x 102 J 6.010 x 103J 4.321 x 103 J

What is the average kinetic energy of 1 mole of a gas at -32 degrees Celsius? (R = 8.314 J/K-mol) 3.006 x 103 J -3.997 x 102 J 6.010 x 103J 4.321 x 103 J

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## How do you calculate the coefficient of kinetic friction on an inclined surface?

The gravitational force Fg between two objects is given by the equation:

Fg=(G*m₁*m₂)/r₂, where G=6.67*10^-11 m³ kg⁻¹ s⁻² is the gravitational constant, m₁ and m₂ are the masses of the two bodies and r is the distance between those bodies.

Due to the gravitational attraction the pencil and the eraser will attract if we there is no friction on the surface.

m₁=10 g=0.01 kg is the mass of the pencil
m₂=20 g=0.02 kg is the mass of the eraser
r=2.5 cm = 0.025 m

First we calculate the Fg:

Fg={(6.67*10^-11)*0.01*0.02}/(0.025²)=2.1344*10^-11 N

To get the velocity v of the pencil:

v²=2as, where a is the acceleration of the pencil and s is the path. In our case s=r so we can write:

v²=2ar

a=Fg/m₁= 2.133*10^-9 m/s²

v²=2*(2.133*10^-9)*0.025=1.0665*10^-10

v=√(1.0665*10^-10)=1.0327*10^-5 m/s

We have the velocity and the acceleration, so we can calculate the time t with the equation:

t=v/a=(1.0327*10^-5)/(2.133*10^-9)=4841.6 s

1 hour has 3600 s so when we divide time t in seconds by 3600 we get time T in hours:

T=t/3600=4841.6/3600=1.3449 h.

So the time for the pencil and eraser to touch is T=1.3449 hours.

Also time T can be expressed like T= 1h and 20 mins and 41.64 s

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## A pendulum of 50 cm long consists of small ball of 2kg starts swinging down from height of 45cm at rest. the ball swings down and strikes a bigger ball. what is the maximum kinetic energy of the 2kg bob

A pendulum of 50 cm long consists of small ball of 2kg starts swinging down from height of 45cm at rest. the ball swings down and strikes a bigger ball. what is the maximum kinetic energy of the 2kg bob

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## A ball rolling down an incline has its maximum kinetic energy at

Velocity of plane = 30.93 m/s

Explanation:

Considering vertical motion of ball

Initial velocity, u =  0 m/s

Acceleration , a = 9.81 m/s²

Displacement, s = 195 m

We have equation of motion s= ut + 0.5 at²

Substituting

s= ut + 0.5 at²

195 = 0 x t + 0.5 x 9.81 x t²

t = 6.31 seconds

Now considering horizontal motion of ball

Acceleration , a = 0 m/s²

Displacement, s = 195 m

Time, t = 6.31 s

We have equation of motion s= ut + 0.5 at²

Substituting

s= ut + 0.5 at²

195 = u x 6.31 + 0.5 x 0 x 6.31²

u = 30.93 m/s

Velocity of plane is horizontal initial speed of ball = 30.93 m/s

Velocity of plane = 30.93 m/s

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## A bowling ball weighs 7.26 kg and takes 3.64 seconds to travel the 19.2 m length of the bowling alley. assuming the velocity is constant, what is the kinetic energy of the bowling ball?

The gravitational force Fg between two objects is given by the equation:

Fg=(G*m₁*m₂)/r₂, where G=6.67*10^-11 m³ kg⁻¹ s⁻² is the gravitational constant, m₁ and m₂ are the masses of the two bodies and r is the distance between those bodies.

Due to the gravitational attraction the pencil and the eraser will attract if we there is no friction on the surface.

m₁=10 g=0.01 kg is the mass of the pencil
m₂=20 g=0.02 kg is the mass of the eraser
r=2.5 cm = 0.025 m

First we calculate the Fg:

Fg={(6.67*10^-11)*0.01*0.02}/(0.025²)=2.1344*10^-11 N

To get the velocity v of the pencil:

v²=2as, where a is the acceleration of the pencil and s is the path. In our case s=r so we can write:

v²=2ar

a=Fg/m₁= 2.133*10^-9 m/s²

v²=2*(2.133*10^-9)*0.025=1.0665*10^-10

v=√(1.0665*10^-10)=1.0327*10^-5 m/s

We have the velocity and the acceleration, so we can calculate the time t with the equation:

t=v/a=(1.0327*10^-5)/(2.133*10^-9)=4841.6 s

1 hour has 3600 s so when we divide time t in seconds by 3600 we get time T in hours:

T=t/3600=4841.6/3600=1.3449 h.

So the time for the pencil and eraser to touch is T=1.3449 hours.

Also time T can be expressed like T= 1h and 20 mins and 41.64 s

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## Nuclear binding energy is necessary to overcome which of the following A. Einstain’s mass defect B. Kinetic energy of the nucleus C. Repulsion of the protons D.weak nuclear force

The unknown of this problem is the experimental percent of water in the compound in order to remove the water of hydrogen, given the following:

Mass of crucible, cover and contents before heating                               23.54 g
Mass of empty crucible and cover                                                            18.82 g
Mass of crucible, cover, and contents after heating to constant mass     20.94 g

In order to get the answer, determine the following:

Mass of hydrated salt used                          = 23.54 g – 18.82 g = 4.72 g
Mass of dehydrated salt after heating          = 20.94 g – 18.82 g = 2.12 g
Mass of water liberated from salt                 = 4.72 g – 2.12 g = 2.60 g

Then solve the percent of water in the hydrated salt by:

% water = (mass of water / mass of hydrated salt) x 100
% water = 2.60 g / 4.72 g x 100
% water = 55.08 % in the compound

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## The observation that ethanol (C2H5OH) has a higher vapor pressure than water (H2O) at the same temperature is due to more A. Hydrogen bonding in the water B. Kinetic energy in the ethanol C. London forces in the ethanol D. Hydrogen bonding in the ethanol E. London forces in the water What is the correct order for the surface tension of the following substances? A. Hg, C8H18, H2O B. Hg, H2O, C8H18 C. C8H18, H2O, Hg D. C8H18, Hg, H20 E. H2O, Hg, C8H18

This problem is to apply Roult’s Law.

Roult’s Law states that the vapor pressure, p, of a solution of a non-volatile solute is equal to the vapor pressure of the pure solvent, Po solv, times the mole fraction of the solvent, Xsolv

p = Xsolv * Po sol

X solv = number of moles of solvent / number of moles of solution

The solvent is water and the solute (not volatile) is glycerin.

Number of moles = mass in grams / molar mass

mass of water = 132 ml * 1 g/ml = 132 g

molar mass of water = 18 g/mol

=> number of moles of water = 132 g / 18 g/mol = 7.33333 mol

mass of glycerin = 27.2 g

molar mass of glycerin:, C3H8O3: 3 * 12 g/mol + 8 * 1 g/mol + 3*16 g/mol = 92 g/mol

number of moles of glycerin = 27.2g / 92 g/mol = 0.29565

total number of moles = 7.33333 moles + 0.29565 moles = 7.62898 moles

=> X solv = 7.33333 / 7.62898 = 0.96125

=> p = 0.96125 * 31.8 torr ≈ 30.57 torr ≈ 30.6 torr.

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## Glucose contains ________. a. osmotic energy b. kinetic energy c. potential energy d. both osmotic and kinetic energy

Explanation:

adenosine triphosphate(ATP) molecule acts as the energy currency for the cell because the energy needed for the various types of functions in the body and for the metabolism process is provided in the form, of adenosine triphosphate.

adenosine triphosphate is an organic molecule that stores energy which is used by the body to perform various activities.

adenosine triphosphate(ATP) is produced by  a process called oxidative phosphorylation with help of an enzyme ATP synthase

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## If a 20 gram bird qnd a 0.001 gram mosquito are moving at the same speed, which has a higher kinetic energy? Why?

If a 20 gram bird qnd a 0.001 gram mosquito are moving at the same speed, which has a higher kinetic energy? Why?

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## BRANLIEST GETS 55 POINTS!!! HELP ASAP!!! Question: What can you learn about kinetic energy? For example, what other types of forces affect kinetic energy? Use research materials to answer you question. Your experiment must be written so that another group can complete the experiment by following your instructions. My question is: _________________________________ _________________________________ How can I test it: _________________________________ _________________________________ My conclusions are: _________________________________ _________________________________

Latitudes, cloud cover, seasons and water vapor

Explanation:

The factors that affect the amount of incoming solar energy reaching on the surface of the earth are as follows-

1) Latitude- The latitude plays an important role in controlling the incoming solar radiation. The places at the equatorial regions experience more heat energy as the sunlight is directly incident on this region. The polar regions receive lesser solar energy because it becomes difficult for the light to reach that region.

2) Clouds- Clouds acts as albedo as it has the property to reflect solar light back into the atmosphere, thereby keeping the surface comparatively cooler.

3) Season- Season occurs due to the tiltation of the earth. season changes when the earth changes its position relative to the sun. In the summer and spring, the tilt of the earth is towards the northern hemisphere and sunlight is maximum in this region. So it receives more amount of solar energy. Whereas autumn and winter remains comparatively cooler.

4) Water vapor- The presence of water vapor in the atmosphere leads to an increase in the absorption of solar energy. When water vapor is less, it receives less solar energy.

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## Kinetic energy is a. the form of energy that actually does work. b. movement of ions or electrons. c. energy that flows between objects with different temperatures. d. stored energy that could do work but is not doing so. e. energy that moves in waves.

sum of kinetic energy and the potential energy

Explanation:

The sum of the kinetic energy and the potential energy is known as the mechanical energy.

The energy of a body possessed by the body by virtue of its position or configuration is called the potential energy of the body.

The formula for the potential energy is given by

U = m x g x h

where, m is the mass of the body, h be the height of the body and g be the acceleration due to gravity.

The energy of the body possessed by the motion of the body is called its kinetic energy. The formula for the kinetic energy is given by

K = 0.5 x m xv^2

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## Calculate the kinetic energy of a 100.0-kg meteor approaching the Earth at a speed of 10.0 km/s.

Answer : The correct option is, Velocity.

Explanation :

Acceleration : It is defined as the rate of change of velocity of an object wit respect to the time. Acceleration is a vector quantity that means it depends on the magnitude and direction of an object. The S.I unit of acceleration is,

Distance : It is defined as the how far an object has traveled in time. Distance is a scalar quantity that means it is depends on the magnitude of an object only. The S.I unit of distance is,

Speed : It is defined as the distance traveled by an object in unit time. Speed is also a scalar quantity. The S.I unit of speed is,

Velocity : It is defined as the change in the position with respect to the time. Velocity is a vector quantity that means it depends on the magnitude and direction of an object. The S.I unit of velocity is,

Mary traveled 70 miles/hour due north. This is an example of velocity. 70 miles/hour tell us about the magnitude of the object and north tell us about the direction of an object.

Hence, the correct option is, velocity.

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