A 40kg girl and a 50kg boy are facing each other on a friction-free rollerskates. The girl pushes the boy, who moves away at a speed of 3 m/s. What is the girl's
speed?
Your answer

Answers

Answer 1

Answer:

Explanation:

The Law of Momentum Conservation, just like the Law of Thermodynamics about energy, says that momentum is neither created nor destroyed but is conserved, meaning it has to go somewhere. If the girl pushes the boy and they are both on friction free skates, then the girl will also react to the push. Momentum Conservation says

[tex](m_gv_g+m_bv_b)_b=(m_gv_g+m_bv_b)_a[/tex] In words this says that the mass times the velocity of the girl plus the mass times the velocity of the boy before the push has to equal the mass times velocity of the girl plus the mass times velocity of the boy after the push. Mathematically,

[tex](40.0*0+50.0*0)_b=(40.0v+50.0*-3)_a[/tex]

The left side of this is equal to 0. On the right, I made the velocity of the boy negative. We could have made it positive and it wouldn't have mattered. The sign will only be important to the result because if the sign of the girl's velocity is the same as the boy's, she is moving in the same direction as he is; if it's different, she is moving in the opposite direction.

0 = 40.0v - 150.0 and

-40.0v = -150.0 so

v = 3.75 This means that when she pushes the boy one way, mometum is conserved and she moves in the opposite direction and at a greater velocity (because her mass is less). Physics is a wonderful thing, isn't it!?


Related Questions

A rope horizontally pulls a massive object lying on a surface with friction with a constant
velocity. What describes the force on the rope?

Answers

Answer:

Equal to the frictional force

Explanation:

Question; The options given with regards to a similar question posted online are;

A. Equal (equivalent) to the frictional force

B. Larger than the frictional force

C. Equal to the object's weight

D. More than the object's weight

Explanation

According to Newton's first law of motion, every object shall remain at rest or continue moving with uniform (constant speed) motion unless there is a net force acting on the object

Given that the velocity of the massive block, lying on the surface that has friction, being pulled by the rope = Constant

Therefore;

The net force acting on the moving block while being pulled by the rope = 0

From which we have;

The pulling force = The resistive force

Where;

The pulling force = The (pulling) force (applied) on the rope

The resistive force = The frictional force of the surface which tends to prevent the motion of the block

Therefore, given that the net force acting on the block = 0

The force on the rope = The frictional force (of the surface)

The correct option is option A. Equal to the frictional force.

What is a sound wave?

Answers

A sound wave is the pattern of disturbance caused by the movement of energy traveling through a medium (such as air, water, or any other liquid or solid matter) as it propagates away from the source of the sound. The source is some object that causes a vibration, such as a ringing telephone, or a person's vocal chords.

What quantities are needed to calculate angular momentum? There is more than one answer.

A.
Radius

B.
Acceleration

C.
Mass

D.
Velocity

Answers

Answer

Velocity, Mass, and Radius

Explanation:

radius is what the size of the thing moving and the mass and velocity is both part of momentum because of speed and direction, BUT acceleration is both the change in speed and direction, not speed for direction themselves, so it is Velocity, Mass, and Radius

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A crate of mass 2 kg is being pulled to the right across a rough horizontal surface by constant force F. The force F is applied at an angle of 20° to the horizontal, as shown in the diagram. how can l draw a labelled free body showing all force​

Answers

Explanation:

Finding the (maximum) respective prime powers would yield the answer. Also we need not ... Is perfectly divisible by 720^n? ... So we can say that for any positive value of n it not

divisible.

What is work and give an example? (science newton's law)

Answers

Answer:

Work is ability if application of energy.

Such as pushing a wheel barrow through a distance ( Newton's third law )

Work is the ability to do something.

what is substances ?????

Answers

Substance:-

A substance is matter which has a specific composition and specific properties.

Can someone help me :)

Answers

Answer:

undergone a chemical change

Explanation:

Answer:

undergone a chemical change

what is accerlation due to gravity?? ​

Answers

Answer:

When an object falls, gravity pulls the object towards the ground and causes the object to accelerate by 9.8m/s each second. Regardless of mass, every object accelerates at the same rate (9.8m/s) when dropped unless there´s air resistance.  

Trafegando por uma avenida com velocidade constante de 54km/h, num dado instante, o motorista percebe o sinal vermelho à sua frente e pisa no freio até que, depois de 5 s, o automóvel para. Determine a aceleração escalar média do carro nesse intervalo de tempo em Km/h dividido por s e em m/s²

Answers

Answer:

The acceleration is - 3 m/s2.

Explanation:

initial speed, u = 54 km/h = 15 m/s

final speed, v = 0

time, t = 5 s

Let the acceleration is a.

use first equation of motion

v = u + at

0 = 15 + a x 5

a = - 3 m/s2

Which of earths spheres are involved in the water cycle

Answers

Answer:

All of the major spheres of the Earth are involved in the water cycle. The four spheres are the atmosphere, hydrosphere, lithosphere, and biosphere....

Explanation:

pa follow thanks ☺️

Which of earths spheres are involved in the water cycle ?

Hydrosphere, atmosphere, lithosphere, and biosphere are all sphere involved in the water cycle.

What is Hydrosphere ?

Hydrosphere is a discontinuous layer of water at or near Earth’s surface. It includes all liquid and frozen surface waters, groundwater held in soil and rock, and atmospheric water vapour.

What is atmosphere?

Atmosphere refers to the gases surrounding a star or planetary body held in place by gravity. ... The composition of the Earth's atmosphere is about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, with water vapor, carbon dioxide, and other gases.

What is lithosphere?

A lithosphere is the rigid, outermost shell of a terrestrial-type planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.

What is Biosphere?

The biosphere, also known as the ecosphere, is the worldwide sum of all ecosystems. It can also be termed the zone of life on Earth. The biosphere is virtually a closed system with regards to matter, with minimal inputs and outputs.

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Tom is throwing an baseball at an aluminum can,
present an argument about the likely kinetic energy of the ball before and after.
describe the evidence that would support the argument.
present an argument about the likely kinetic energy of the can before and after.
describe the evidence that would support the argument.

Answers

Answer:

The question relates to the conservation of energy principle, the conservation of the linear momentum, and Newton's Laws of motion

Part A

1) Tom throwing a baseball at a can

The initial velocity of the baseball = v₂

The initial kinetic energy of the baseball, K.E.₂ = (1/2)·m₂·v₂²

∴ The final kinetic energy of the baseball, K.E.₂' = (1/2)·m₂·v₂'² < (1/2)·m₂·v₂²

Therefore, the energy of the ball before the collision is lesser than the energy of the ball after the collision

2) The evidence that would likely support the claim is that the baseball's height above the ground reduces rapidly immediately after the collision which is due to the reduced velocity, and therefore, the reduced (kinetic) energy

The final velocity of the baseball v₂' < v₂

Part B

1) The argument

The initial velocity of the can = v₁ = 0 (The can is initially  at rest)

The initial kinetic energy of the can, K.E.₁ = (1/2)·m₁·v₁² = 0

The final velocity of the can v₁' > v₁ = 0

∴ The final kinetic energy of the can, K.E.₁ = (1/2)·m₁·v₁² > 0

Given that the velocity of the can increases from zero to a positive value after collision with the baseball, the kinetic energy of the can is increased from zero before the collision to a positive value after the collision

2) An evidence in support of the argument is the motion of the can which was initially at rest which is an indication of increase in energy podded by the can

Explanation:

Dierks is a scientist who is currently focusing on developing a ceramic that holds heat well. He is trying to develop the ceramic to make a higher-temperature curling iron. The application of solid-state physics Dierks is most likely involved in is (BLANK).

Answers

Answer:

i need this 2

Explanation:

Answer:

Materials Science

Explanation:

Materials Science: "The study of the characteristics of materials such as glass, plastics, and metals."

Ceramics is a glass so they are studying materials science.

Hope this helped ! :)

A ball at rest has a mass of 2.5 kg. Determine the force required to accelerate the ball to 2.5 m/s?

Answers

Answer:

6.25 N

Explanation:

F = ma

F = 2.5 × 2.5

F = 6.25 Newtons

define pressure snd state its SI units to​

Answers

Pressure is defined as the perpendicular force acting per unit area.

Its SI unit is pascal.

Explanation:

Formula to calculate pressure is,

P=F/A

Where as,

P = Pressure

F = Force

A = Area

Its SI unit is pascal(pa).

How much pressure is created by a circular piston that is 0.24 meter in diameter
with a Force of 200.0 N? N/m2 ... (round answer to nearest ones place -no decimal)

Answers

Answer:

4000 N/m²

Explanation:

Area = πr²

Area = π x 0.12² (diameter/2)

Area = 0.05 m²

Pressure = force/area

Pressure = 200/0.05

Pressure = 4000 N/m²

Hope this helps!

A certain AM radio wave has a frequency of 24Hz. Given that radio waves travel at 3 m/s, what is the wavelength of this radio wave?

Answers

Answer:

Wavelength of AM radio wave = 0.125 meter

Explanation:

Given:

Frequency of AM radio wave = 24 Hz

Velocity of AM radio wave = 3 m/s

Find:

Wavelength of AM radio wave

Computation:

Wavelength = Velocity / Frequency

Wavelength of AM radio wave = Velocity of AM radio wave / Frequency of AM radio wave

Wavelength of AM radio wave = 3 / 24

Wavelength of AM radio wave = 0.125 meter

¿Cuál es la presión que soporta un buzo sumergido a 10 metros de profundidad en el mar? Datos: Densidad del agua de mar = 1025 kg/m^3 Presión atmosférica 101325 Pa Y por que

Answers

Answer:

The pressure at the depth is 201775 Pa.

Explanation:

Depth, h = 10 m

density, d = 1025 kg/m3

atmospheric pressure, Po = 101325 Pa

The total pressure at the depth is

P = Po + h d g

P = 101325 + 10 x 1025 x 9.8

P = 101325 + 100450

P = 201775 Pa

The distance between an object and a reference point is the object's what?

Answers

Answer:

Displacement

Explanation:

The distance between an object and a certain reference point is called displacement. This is not to be confused with distance, which represents the total distance the object has travelled to get a certain point, regardless of how long it is. Displacement always represents the shortest distance (a straight line) between the initial and final points.

Answer:

Displacement is the distance and direction of an object's change in position from a reference point. Suppose a runner jogs to the 50-m mark and then turns around and runs back to the 20-m mark.

Which statement describes the possible interaction(s) between two objects
caused by the electric, magnetic, or gravitational force between them?
O A. Electric and gravitational forces only cause objects to repel each
other, and magnetic forces only cause objects to be attracted to
each other.
O B. All three types of forces only cause the objects to repel each other.
O C. Gravitational forces only cause objects to be attracted to each
other, and magnetic and electric forces can cause objects to
attract or repel each other.
O D. All three types of forces only cause the objects to be attrachyd to
each other.

Answers

The statement which describes the possible interaction(s) between two objects caused by the electric, magnetic, or gravitational force between them is:

Gravitational forces only cause objects to be attracted to each other, and magnetic and electric forces can cause objects to

What is force?

Force can be defined as the push or pull on an object with mass that causes it to change its velocity

So therefore, the statement which describes the possible interaction(s) between two objects caused by the electric, magnetic, or gravitational force between them is:

Gravitational forces only cause objects to be attracted to each

other, and magnetic and electric forces can cause objects to

Learn more force:

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When do we say that work is done?​

Answers

Answer:

Work is said to be done when a force applied to an object moves that object. We can calculate work by multiplying the force by the movement of the object.

Answer:

Work is done by a force on an object if (i) a force acts on the object and (ii) the object is displaced from its original position

For the normal force in the drawing to have the same magnitude at all points on the vertical track, the stunt driver must adjust the speed to be different at different points. Suppose, for example, that the track has a radius of 3.25 m and that the driver goes past point 1 at the bottom with a speed of 20.2 m/s. What speed must she have at point 3, so that the normal force at the top has the same magnitude as it did at the bottom

Answers

Answer:

The speed she must have at point 3 is approximately 21.72 m/s

Explanation:

The given parameters are;

The radius of the track, r = 3.25 m

The speed with which the driver goes past point 1, v₁ = 20.2 m/s

Let, 'm', represent the mass of the driver and the car, and let v₃ represent the velocity at point 3, based on the diagram and solution method from a similar question online, we have;

At point 1, The net force, [tex]F_{NET} = F_N - F_g[/tex]

The net force, [tex]F_{NET}[/tex], is the centrifugal force, therefore;

[tex]F_{NET} = \dfrac{m \cdot v_1^2}{r}[/tex]

[tex]F_g[/tex] = The force of gravity on the car (the weight of the car) = m·g

[tex]F_N_1[/tex] = The normal reaction at point 1

Therefore, we have;

[tex]F_{NET} = \dfrac{m \cdot v_1^2}{r} = F_N_1 - F_g = F_N_1 - m \cdot g[/tex]

[tex]F_N_1= \dfrac{m \cdot v_1^2}{r} + m \cdot g = m\cdot \left(\dfrac{ v_1^2}{r} + g \right)[/tex]

[tex]F_N_1 = m\cdot \left(\dfrac{ v_1^2}{r} + g \right)[/tex]

At point 3, The net force, [tex]F_{NET} = F_N_3 + F_g[/tex]

Where;

[tex]F_{N3}[/tex] = The normal reaction at point 3

Therefore;

[tex]F_N_3= F_{NET} - F_g = \dfrac{m \cdot v_3^2}{r} - m \cdot g = m\cdot \left(\dfrac{ v_3^2}{r} - g \right)[/tex]

For the normal force to be the same, we get;

[tex]F_{N1} = F_{N3}[/tex]

Therefore;

[tex]m\cdot \left(\dfrac{ v_1^2}{r} + g \right) = m\cdot \left(\dfrac{ v_3^2}{r} - g \right)[/tex]

[tex]\left(\dfrac{ v_1^2}{r} + g \right) = \left(\dfrac{ v_3^2}{r} - g \right)[/tex]

[tex]v_3^2 = r \times \left(\dfrac{ v_1^2}{r} + g + g \right) = v_1^2 + 2\cdot g \cdot r[/tex]

[tex]v_3 = \sqrt{v_1^2 + 2\cdot g \cdot r}[/tex]

Where;

g = The acceleration due to gravity ≈ 9.81 m/s²

Therefore;

v₃ = √(20.2² + 2 × 9.81 × 3.25) ≈ 21.72 m/s

The speed she must have at point 3, so that the normal force at the top has the same magnitude as it did at the bottom, v₃ ≈ 21.72 m/s

Molten iron has a density of 7.0 g/cm. In its solid state, iron has a density of
8.0 g/cm?
Calculate the volume of 10 kg of molten iron.

Volume =​

Answers

Answer: 1250 cm^3

As we know density = mass/ volume

Replacing the value in the above formula

8.0 = 1000/ volume

Here, kilogram needs to converted into mass

Volume = 10000/8

Volume = 1260 cm^3

Determine the value of F
l will give BRAINLIEST.....​

Answers

Answer:

10 N

Explanation:

From the diagram,

Applying the principle of moment,

Sum of clockwise moment = sum of anti clockwise moment.

Assuming: the 10 N is placed on the 5 cm mark, F is placed on the 40 cm mark, The 25 N is placed on the 10 cm mark, the 30 N is placed on the 75 cm mark, and the 40 N is placed on the 80 cm mark.

Therefore,

10(50-5)+F(50-40)+40(80-50) = 30(75-50)+25(50-10)

450+10F+1200 = 750+1000

10F+1650 = 1750

10F = 1750-1650

10F = 100

F = 100/10

F = 10 N

what current flows between a voltage of 120v across a resistance of 30Ω?​

Answers

Answer:

4 amp

Explanation:

From ohm's law,

V=IR

so,

I=V/R

I=120/30

I=4amp ans..

A motor has an internal resistance of 12.1 Ω. The motor is in a circuit with a current of
4.0 Amps
What is the voltage?

Answers

Answer:

Explanation:

V = I * R

V = 4 * 12.1 = 48.4 v

Cuatro contenedores idénticos tienen la misma cantidad de gas helio a la misma temperatura inicial. Los recipientes también cuentan con un émbolo móvil que no permite que el helio escape. Cada muestra de gas sigue un proceso distinto como se describe a continuación: Muestra 1: 500 J de calor salen del gas y este realiza 300 J de trabajo. Muestra 2: 500 J de calor entran al gas y este realiza 300 J de trabajo. Muestra 3: 500 J de calor salen del gas y se hace un trabajo de 300 J sobre él. Muestra 4: 500 J de calor entran al gas y se hace un trabajo de 300 J sobre él.

Answers

Answer:

1)  ΔE = -800 J, 2) ΔE = 200 J, 3)  ΔE = -200 J, 4) ΔE = 800 J

Explanation:

For this exercise let's use the first law of thermodynamics

             

          ΔE = Q + W

Where we will apply this expression to several cases

1) output Q = 500 J and does work of W = 300 J.

The two processes involve an energy output

         ΔE = - 500 - 300

         ΔE = -800 J

Therefore, the internal energy of the gas decreases by this amount,

2) enter Q = 500J and do work of W = 300 J

         Positive heat is added and does negative work

         ΔE = 500 - 300

         ΔE = 200 J

3) they leave Q = 500 J and do (work on the gas) W = 300J

negative heat and positive work come out

          ΔE = -500 + 300

          ΔE = -200 J

4) heat enters Q = 500 J, work on gas W = 300 J

both positive

         ΔE = 500 + 300

         ΔE = 800 J

You might have noticed that a feather falls slowly toward the ground, while a ball falls rapidly. Which statement correctly explains the motion of these objects?

1. The ball does not experience fluid friction as it falls.
2. Gravity is the only force acting on the feather and the ball.
3.The acceleration of the ball and feather are the same.
4. The feather experiences more fluid friction than the ball.

Answers

Answer:

4. the feather experiences more fluid friction than the ball

A first aid provider is trained to do the following except:
A) diagnose the victims condition
B) recognize, asses and prioritize the need for first aid
C) seek professional medical assistance when necessary
D) provide appropriate first aid care

Answers

A.
They’re supposed to help the person and cannot diagnose them as that is the job of a doctor

In an electrical circuit 200mC of charge flows through a 50kohm resistor in 90 seconds. What is the power

Answers

Answer: [tex]0.2464\ W[/tex]

Explanation:

Given

Charge [tex]Q=200\ mC[/tex]

Resistance [tex]R=50\ k\Omega[/tex]

Time [tex]t=90\ s[/tex]

Charge is the amount of current flown in a particular time

[tex]Q=It\\\Rightarrow 200\times 10^{-3}=I\times 90\\\\\Rightarrow I=\dfrac{200\times 10^{-3}}{90}\\\\\Rightarrow I=2.22\times 10^{-3}\ A[/tex]

Power is the given by [tex]P=I^2R[/tex]

Insert values

[tex]\Rightarrow P=\left(2.22\times 10^{-3}\right)^2\times 50\times 10^3\\\\\Rightarrow P=246.42\times 10^{-3}\ W\\\\\Rightarrow P=0.2464\ W[/tex]

The power is in the circuit is [tex]0.2464\ W[/tex].

a man runs 1200m on a straight line in 4 min . find his velocity.

Answers

Answer:

5m/sec^2

Explanation:

Distance=1200m

Time=4 min

1=60sec

4=4 x 60

=240sec

Velocity=Distance/Time

Velocity=1200/240

Velocity=5m/sec^2

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