skater with a mass of 50.0 kg slides across an icy
pond with negligible friction. As he approaches a
friend, both he and his friend hold out their hands,
and the friend exerts a force in the direction oppo-
site to the skater's movement, which slows the skat-
er's speed from 2.0 m/s to 1.0 m/s. What is the
change in the skater's kinetic energy?
A. –25 J
C. – 100J
B. -75J
D. -150J​

Answer:

-mg = -7.52*9.8 = - 73.696N

Answer:

See image

Explanation:

Plato

Answer:

Force = 12.5 Newton

Explanation:

Given the following data;

Mass = 250 g to kilograms = 250/1000 = 0.25 kg

Acceleration = 50 m/s²

To find the force;

Newton's Second Law of Motion states that the acceleration of a physical object is directly proportional to the net force acting on the physical object and inversely proportional to its mass.

Mathematically, it is given by the formula;

[tex] Acceleration = \frac {Net \; force}{mass} [/tex]

Making force the subject of formula, we have;

[tex] Force = mass * acceleration [/tex]

Substituting into the formula, we have

[tex] Force = 0.25 * 50 [/tex]

Force = 12.5 Newton

Answer:

B. Uranium 238.

Explanation:

It is radioactive and can be used to treat cancer in the form of radiotherapy

Explanation:

i. Vi=24

Vf=0

t= -2

a=vf-vi/t =0-24/12 = -2m/S2

ii. F=ma = 1500×-2= -3000 N

Answer:

Pressure = ρgh

pressure (p) is measured in pascals (Pa)

density (ρ) is measured in kilograms per metre cubed (kg/m3)

The fore of gravitational field strength (g) is measured in N/kg or m/s 2

height of column (h) is measured in metres (m)

Answer = 235,200 Pa

Explanation:

Pressure = ρgh

Pressure = 1,000 x 9.8 x 24

Pressure = 235,200 Pa

Answer:

Moment is an expression involving the product of a distance and physical quantityA moment is due to a force not having an equal and opposite force directly along it's line of action. ... It is defined as the product of the force (F) and the moment arm (d). The moment arm or lever arm is the perpendicular distance between the line of action of the force and the center of moments.Moments act about a point in a clockwise or anticlockwise direction.

Answer: A ( how to pedal and balance )

Explanation:

Answer:

electron

Explanation:

The electron is the subatomic particle with the least mass. Therefore option A is correct.

Both protons and neutrons have significantly larger masses compared to electrons.

The mass of an electron is approximately 9.1 x 10^-31 kilograms, while the mass of a proton is about 1.67 x 10^-27 kilograms, and the mass of a neutron is also around 1.67 x 10^-27 kilograms.

It's important to note that the "atom" is not a subatomic particle but a structure composed of subatomic particles. An atom consists of a nucleus (composed of protons and neutrons) and electrons orbiting around the nucleus.

The mass of an atom depends on the number of protons, neutrons, and electrons it contains, so it can vary widely depending on the specific atom.

In summary, when comparing individual subatomic particles, the electron has the least mass.

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Answer:

Consequently the statement is FALSE

Explanation:

The process of emission of electrons or photoelectric effect, was explained by Einstein, assuming that light behaves as formed by how many so-called photons and each one of them collides with an electron, therefore to start an electron the incident photon energy must be greater than the work function of the material.

            E =K + Ф

By mentioning the intensity we increase the number of photons but we do not increase their energy.

Consequently the statement is FALSE

Complete question is;

A sudden loud sound such as an explosion can damage the ear, as can long-term exposure to high levels of sound.

A) True

B) False

Answer:

True

Explanation:

This sudden sound described in the question is usually referred to as an impulse sound which can cause damage to hearing. Furthermore, it can lead to a type of hearing loss where one experiences buzzing, roaring or ringing sounds in one's ears.

Thus the statement in the question is true.

Answer:

the angular acceleration of the car is 1.5 rad/s²

Explanation:

Given;

initial angular velocity, [tex]\omega_i[/tex] = 10 rad/s

final angular velocity, [tex]\omega_f[/tex] = 25 rad/s

time of motion, t = 10 s

The angular acceleration of the car is calculated as follows;

[tex]a_r = \frac{\omega_f - \omega_i }{t} \\\\a_r = \frac{25-10}{10} = 1.5 \ rad/s^2[/tex]

Therefore, the angular acceleration of the car is 1.5 rad/s²

Answer:

It is because some of the heat is lost in the surroundings.

Explanation:

To calculate the specific heat of the metal, the following steps are performed.

Take a piece of metal whose mass and the initial temperature is known.

Now take a beaker filled with some measured amount of water and the temperature of water is known.

Drop the heated metal piece in the water so that the equilibrium is reached.

According to the principle of calorimetery,

Heat lost by the metal = heat gained by the water

here, some of the heat is lost in the surroundings so we don't get the correct value of the specific heta of the metal.

Answer

225 meters.

Explanation:

x=x0+30t-(1/2)(1.5)t^2

x=0+30(10)-(1/2)(1.5)(10)^2

x=300-75

x=225

Answer:

I don't understand the Question

Answer:

C. A sock sticks to a pair of pants after both are removed from the

clothes dryer.

Explanation:

there is influence of charges

Answer:

The iron bolt is attracted to the electromagnet. The force of attraction between the electromagnet's core and the iron bolt is greater than the force of the spring, so the iron bolt is pulled out of its housing in the door

Explanation:

Answer:

amu is atomic mass unit

All of elements hydrogen is the lightest.

Hydrogen is taken as a basic unit so it happened 1amu

So 1 amu must be hydrogen mass

If I am wrong,Pls tell me the true answer....

Answer:

D. Energy in an isolated system remains constant.

Explanation:

Energy can be defined as the ability (capacity) to do work. The two (2) main types of energy are;

a. Gravitational potential energy (GPE): it is an energy possessed by an object or body due to its position above the earth.

b. Kinetic energy (KE): it is an energy possessed by an object or body due to its motion.

Furthermore, the various forms of energy are solar energy, electrical energy, chemical energy, thermal energy, wind energy, nuclear energy etc.

The Law of Conservation of Energy states that energy cannot be destroyed but can only be transformed or converted from one form to another.

According to the law of conservation of energy, we can infer or deduce that the total energy of the system must stay the same because it cannot be destroyed, but kinetic energy (KE) can be transformed to potential energy (PE) and potential energy (PE) can be transformed to kinetic energy (KE) within the system.

Answer:

a region around a magnetic material or a moving electric charge within which the force of magnetism acts.

Explanation:

The definition of a magnetic field is a place in space near a magnet or an electric current where a physical field is created from a moving electric charge that creates a force on another moving electric charge. An example of a magnetic field is the Earth's magnetic field.

Answer:

A

Explanation:

the object's mass determines the speed of the object and its kinetic energy

Answer:

All of them are false

Explanation:

4. electrons flow from earth to the object

5. electrons move freely

6. protons can't move

Answer:

They all false

Answer:

Explanation:

The gravitational force equation is

[tex]F_g=\frac{Gm_1m_2}{r^2}[/tex] where G is the gravitational constant. Filling in with what we are given and what we know to be true:

[tex]F_g=\frac{6.67*10^{-11}(59)(59)}{(2.0)^2}[/tex] which, when you do the math, comes out to be

[tex]F_g=5.8*10^{-8}N[/tex], choice A.

Answer:

1= Kidneys

2= Ureters

3=Bladders

4=Urethra

Explanation:

Functions of kidney: Regulations of water balances, excretions of nitrogenous wastes(urea)

Functions of Liver: Detoxifications, protein synthesis

Functions of Skin: Temperature regulations, Metabolic functions, Excretion

Functions of lungs: Respiration, Water balance regulations

Tip: If you want faster and correct answers you should label your questions under the correct subject.

Answer:

34902

Explanation:

Pv=nRt

v=nrt/p

subsitute

v=15*831*280/100

v=34902

Answer:

40 m

Explanation:

The area under v-t graph gives the distance travelled by the particle.

Distance = area of ΔOBC + area of ΔCDE + area of ΔEFG

[tex]=\dfrac{1}{2}\times 4\times 10+\dfrac{1}{2}\times 2\times 10+\dfrac{1}{2}\times 4\times 5\\\\=40\ m[/tex]

So, the distance travelled by the particle in the time interval t = 0 and t= 10 s is equal to 40 m.

Answer:

Oh, umm…

Jump! (The higher, the better!)

Drop your pencil! (or pen or ruler, whichever you prefer!)

Throw a ball of paper! (and make sure you pick it back up later!)

Explanation:

if you satisfied to my answer , just put brainliest please , and ur welcomeee♥️♥️

Answer:

Energy is: the ability to do work

The formula for energy is: power x time = energy

Explanation:

Hope this helps (there isn't really an explanation)

Answer:

False

Explanation:

I'm not the most sure but it seems reasonable that it's false

Good Luck Bestie :3

Answer:

The answer is false. If you want why. I will desxribe you.

Answer:

a.

[tex]F=G\cdot\dfrac{M \cdot m}{r^{2}}[/tex]

b.

[tex]F=6.67430 \times 10^{-11} \dfrac{N \cdot m^2}{kg^2} \times \dfrac{5.97 \times 10^{24} \ kg \times 1,300 \ kg}{(6,578 \ m)^{2}}[/tex]

c.

[tex]F=6.67430 \times 10^{-11} \dfrac{N \cdot m^2}{kg^2} \times \dfrac{5.97 \times 10^{24} \ kg \times 1,300 \ kg}{(6,578 \ m)^{2}} \approx 1.144 \times 10^{13} \ N[/tex]

d. The force of gravity acting on the satellite is approximately 1.144 × 10¹³ N

Explanation:

a. The formula for finding the force of gravity, F, acting object on an object is given as follows;

[tex]F=G\cdot\dfrac{M \cdot m}{r^{2}}[/tex]

Where;

F = The force acting between the Earth and the object

G = The gravitational constant = 6.67430 × 10⁻¹¹ N·m²/kg²

M = The mass of the Earth = 5.97 × 10²⁴ kg

m = The mass of the object

r = The distance between the center of the Earth and the object

b. Finding the gravitational force, 'F', between the Earth and the scientific satellite, we have;

The given mass of the satellite, m = 1,300 kg

The distance between the center of the Earth and the center of the satellite,  r = The length of the radius of the Earth + The height of orbit of the satellite

The given height of orbit of the satellite, h = 200 km

∴ r = R + h = 6,378 km + 200 km = 6,578 m

Therefore, by plugging in the values, we get;

[tex]F=6.67430 \times 10^{-11} \dfrac{N \cdot m^2}{kg^2} \times \dfrac{5.97 \times 10^{24} \ kg \times 1,300 \ kg}{(6,578 \ m)^{2}}[/tex]

c. Solving the above equation gives;

[tex]F=6.67430 \times 10^{-11} \dfrac{N \cdot m^2}{kg^2} \times \dfrac{5.97 \times 10^{24} \ kg \times 1,300 \ kg}{(6,578 \ m)^{2}} \approx 1.144 \times 10^{13} \ N[/tex]

d. The force of gravity acting on the satellite, F ≈ 1.144 × 10¹³ Newton

Answer:

3. ultraviolet and x rays

The two forms of electromagnetic energy are used to produce the most spectacular fluorescence when placed in darkness are ultraviolet and x rays.

Electromagnetic radiation is waves of the electromagnetic field, propagating through space, carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, light, ultraviolet, X-rays, and gamma rays.

Fluorescence is the process in which a substance absorbs light at a high energy, short wavelength and emits light at a lower energy, usually visible wavelength.

Ultraviolet rays is a type of electromagnetic waves in which the wavelength is shorter than visible rays. It is responsible for 10% of sunlight and causes sun tan. It is used to purify water in water purifiers. It kill germs.

X rays lies beyond ultraviolet rays. It is used to diagnose in medical field. It can destroy living tissues so excessive exposure should be limited to reduce harmful effect.

The color change of fluorescent minerals is most spectacular when the minerals are placed in darkness and exposed to electromagnetic energy shorter than visible light.

Ultraviolet and x rays are shorter than visible light so they exhibit fluorescent property.

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