*If someone says v-u=0 ,what does it mean. *What is the relation among mometum,mass and velocity. *A moving bus a little distance forward even when breaks are applied on it which Newton's laws work here? *Under what conditions acceleration of a moving object will be zero?

Answer:

The answer is (a.) An upward force balances the downward force gravity on the skydiver

The skydiver is falling at a constant velocity because the upward force is balancing the downward force of gravity. According to Newton, the opposite force balance each other. This is stated in Newton's second law of motion.

The statement that best applies Newton’s laws of motion to explain the skydiver’s motion is that An upward force balances the downward force of gravity on the skydiver.

Newton's 3rd law often applies to skydiving.

When gravity is not acting upon the skydivers they would continue moving in the direction the vehicle they jumped from was moving.

If no air resistance takes place, then the skydivers would still accelerating at 9.8 m/s until they hit the ground.

The skydiver after leaving the aircraft will accelerates downwards due to the force of gravity

usually as there is no air resistance acting in the upwards direction, and there is a resultant force acting downwards, the skydiver will accelerates towards the ground.

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Answer:

borosilicate glass

Explanation:

headlamp glass is a borosilicate glass by gravity feed

[tex] \large{ \boxed{ \bf{ \color{red}{Universal \: law \: of \: gravitation}}}}[/tex]

Every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them. The forces along the line joining the centre of the two objects.

❍ Let us consider two masses m1 and m2 line at a separation distance d. Let the force of attraction between the two objects be F.

According to universal law of gravitation,

[tex] \large{ \longrightarrow{ \rm{F \propto m_1 m_2}}}[/tex]

Also,

[tex] \large{ \longrightarrow{ \rm{ F \propto \dfrac{1}{ {d}^{2} } }}}[/tex]

Combining both, We will get

[tex] \large{ \longrightarrow{ \rm{F \propto \dfrac{ m_1 m_2}{ {d}^{2}}}}} [/tex]

Or, We can write it as,

[tex] \large{ \longrightarrow{ \rm{F \propto \: G \dfrac{ m_1 m_2}{ {d}^{2} }}}}[/tex]

Where, G is the constant of proportionality and it is called 'Universal Gravitational constant'.

☯️ Hence, derived !!

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Answer:  392N

Explanation: W=mg

                 W= 40x9.8

                     = 392N

Answer:

[tex]\large \boxed{\sf 392.4 \ N}[/tex]

Explanation:

[tex]\sf Weight \ (N) =mass \ (kg) \times acceleration \ of \ gravity \ (m/s^2)[/tex]

[tex]W=mg[/tex]

[tex]W=40 \times 9.81[/tex]

[tex]W= 392.4[/tex]

Answer:

The angular acceleration α = 14.7 rad/s²

Explanation:

The torque on the rod τ = Iα where I = moment of inertia of rod = mL²/12 where m =mass of rod  and L = length of rod = 4.00 m. α = angular acceleration of rod

Also, τ = Wr where W = weight of rod = mg and r = center of mass of rod = L/2.

So Iα = Wr

Substituting the value of the variables, we have

mL²α/12 = mgL/2

Simplifying by dividing through by mL, we have

mL²α/12mL = mgL/2mL

Lα/12 = g/2

multiplying both sides by 12, we have

Lα/12 × 12 = g/2 × 12

αL = 6g

α = 6g/L

α = 6 × 9.8 m/s² ÷ 4.00 m

α = 58.8 m/s² ÷ 4.00 m

α = 14.7 rad/s²

So, the angular acceleration α = 14.7 rad/s²

Answer:

F = 9.675Hz

Explanation:

pls for certain reasons let us make

3 loops : 6$/4 = L

6$/4 = 2

$ = 4/3 = 1.333

V = F x $

F = V/$

F = 12.9/1.333 = 9.675Hz

F = 9.675Hz

Answer:

Wavelength = 1 meters

Explanation:

Given that,

Number of oscillations is 5

It passes through a point in 0.5 s

The speed of sound was recorded to be 10 m/s.

We need to find the wavelength of the sound.

Firstly, we will find frequency of this wave. Total no of oscillations per unit time is called frequency. So,

[tex]f=\dfrac{5}{0.5}\\\\f=10\ Hz[/tex]

Now the speed of wave in terms of wavelength and frequency is given by :

[tex]v=f\lambda[/tex]

Here, [tex]\lambda[/tex] = wavelength

[tex]\lambda=\dfrac{v}{f}\\\\\lambda=\dfrac{10\ m/s}{10\ Hz}\\\\\lambda=1\ m[/tex]

So, the wavelength of the sound is 1 meters.

Answer:

The velocity and direction after 1 second is 8.1 m/s downwards

Explanation:

The equation of motion for an object in free fall can be written as follows;

v = u + g×t

Where;

v = The final velocity of the object

u = The initial velocity of the object = 0 m/s

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

The velocity after one second is given by the velocity equation as follows;

v = 0 + 9.81 m/s² * 1 s = 9.81 m/s

The direction of the is downwards due to the attraction by the Earth's gravitational field which acts towards the Earth's center

Therefore, the velocity and direction after 1 second is 8.1 m/s downwards.

Answer:

0 degrees Celsius is 273 degrees Kelvin. As both pressure and volume are proportional to absolute temperature, in order to double both you would need to quadruple the temperature. I.e. 273 X 4 = 1092 Kelvin = 819 Celsius

Explanation:

Answer:

Height of pole = Height of giraffe

Explanation:

Given:

Height of giraffe = 20 ft

Height of pole = 240 inch

Find:

Which is taller

Computation:

Height of giraffe = 20 ft

We know that 1 ft = 12 inch

So,

Height of giraffe = 20 × 12 inch

Height of giraffe = 240 inch

and

Height of pole = 240 inch

Height of pole = Height of giraffe

Answer:

30°

Explanation:

The angle between the normal and the vertical is the same as the angle between the incline and the horizontal.  We can show this with geometry.

Answer:

  #_total = 4.38 10⁹ liter

Explanation:

For this exercise we can use a direct proportion rule (rule of three). If 4 people use 1200 liters how much water 1 person consumes

            #_water = 1 person (1200 liter / 4 person)

            #water = 300 liters

Now we look for the consumption of this person in a year, if 1 person consumes 300 liters 1 day, how many liters they consume in a year (365 days)

           #_water_person_total = 365 days (300 liters / 1 day)

           #_water_person_total = 109500 liters

This is the water consumption of 1 person in a year, the total of 40000 people how much they consume

           #_total = 40000 person (109500 liter / 1 person)

           #_total = 4.38 10⁹ liter

In a food web, the removal of any trophic level upsets the balance within the web and can cause its eventual collapse. Because producers capture solar energy and convert it to food energy, their loss would affect every other level of the food web.

The removal of the producers would cause the collapse of the entire food web. Primary consumers or herbivores, which feed on producers directly, would die off. The next to be affected would be the secondary consumers or carnivores that eat the primary consumers. Higher level consumers would suffer as organisms from lower trophic levels start to die off. Decomposers would break down the bodies of dead organisms, returning their basic elements and compounds to the environment. However, even these dead organisms would run out and the entire food web would collapse.

Hope you like the answer.

Answer:

The time she takes to reach the water from when she jumps off the platform is 1.71 s

Explanation:

According to the equations of motion, we have;

v = u - g·t

v² = u² - 2·g·s

s₁ = u₁·t₁ + 1/2·g₁·t₁²

The given parameters are;

The height of the platform (assumption: above the water) = 10 m

The velocity with which she jumps, u = 3 m/s

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

The height to which she jumps, s, is found as follows;

v² = u² - 2·g·s

At maximum height, v = 0, which gives;

0 = 3² - 2×9.81×s

2×9.81×s = 3² = 9

s = 9/(2×9.81) = 0.4587 m

s = 0.4587 m

The time to maximum height, t, is found as follows;

v = u - g·t

0 = 3 - 9.81×t

9.81×t = 3

t = 3/9.81 = 0.3058 s

The total distance, s₁ from maximum height to the water surface = s + 10 = 0.4587 + 10 = 10.4587 m = 10.46 m

The time to reach the water from maximum height, t₁, is found as follows;

s₁ = u₁·t₁ + 1/2·g₁·t₁²

Where;

s₁ =  The total distance from maximum height to the water surface = 10.46 m

u₁ = The initial velocity, this time from the maximum height = 0 m/s

g₁ = The acceleration due to gravity, g (positive this time as the diver is accelerating down) = 9.81 m/s²

t₁ = The time to reach the water from maximum height

Substituting the values gives;

s₁ = u₁·t₁ + 1/2·g₁·t₁²

10.46 = 0·t₁ + 1/2·9.81·t₁²

t₁²= 10.46/(1/2×9.81) = 2.13 s²

t₁ = √2.13  = 1.46 s

Total time = t₁ + t = 1.46 + 0.3058 = 1.7066 ≈ 1.71 s.

Therefore, the time she takes to reach the water from when she jumps off the platform = 1.71 s.

Answer: Bleach is a base

Explanation:  If bleach had a pH level of 12, a number above 7, than it is a base.  Hope this helps!

Answer:

The evaporation time gradually increased with the increase in surfactant concentration, i.e., from water to the concentration level of 0.005%. Furthermore, the evaporation time is significantly reduced, even lower than that of water containing relatively high concentrations from 0.01% to 0.1%.

Explanation:

We know that,

[tex]hydrostatic \: pressure (p) = \alpha hg [/tex]

Where,

[tex] \alpha = density \: of \: water \: = 1000[/tex]

h = Height at which pressure is to be calculated

[tex]p = 1000 \times 12 \times 9.8 = 117600 \: [/tex]

Answer:

Explanation:

Heat is transferred in the following ways listed below

1. Conduction(Through direct contact of particles )

2. Convection(Through motion of hot and cold liquid )

3. Radiation(Through electromagnetic waves Through the rising of a warm gas )

1. Conduction: This has to do with the transfer of heat from one medium to another having direct contact with each other, the medium can either be solid or liquids

2. Convection: Has to do with the transfer of heat energy via molecules of the liquids in motion with different or varying temperature gradients

3. Radiation: Mostly occurs in gases, it is the transfer of energy through waves

Answer:

Dx/dt  = 4,8 f/s

Explanation:

The ladder placed against a wall, and the ground formed a right triangle

with x and h the legs and L the hypothenuse

Then

L² = x² + h²          (1)

L = 26 f

Taking differentials on both sides of the equation we get

0  = 2x Dx/dt  + 2h Dh/dt    (1)

In this equation

x = 10   distance between the bottom of the ladder and the when we need to find, the rate of the ladder moving away from the wall

Dx/dt is the rate we are looking for

h = ?    The height of the ladder when  x = 10

As    L²  =  x²  + h²

h²  =  L²  -  x²

h²  =  (26)²  - (10)²

h²  =  676  -  100

h²  = 576

h = 24 f

Then equation (1)

0  = 2x Dx/dt  + 2h Dh/dt

2xDx/dt  = -  2h Dh/dt

10 Dx/dt  = - 24 ( -2 )      ( Note the movement of the ladder is downwards)

Dx/dt  =  48/10

Dx/dt  = 4,8 f/s

Answer:

They can be penetrated only with longer wavelengths such as radio and infrared.

Explanation:

A dark nebula can be defined as an interstellar cloud that is so dense as a result of high concentration of gas and dust and as such it obscures the visible wavelengths of light from stars behind it, thus appearing completely opaque (dark patch) in front of a bright emission nebula or in regions having  plenty stars.

Hence, dark nebulae can be penetrated only with longer wavelengths such as radio and infrared light because they cannot be absorbed by the dust layers or particles coated with frozen carbon monoxide and nitrogen residing in the dark nebulae.

Answer:

I do not agree with the answer.

Because in reality, the atom has 2 main parts and 3 subatomic particles.

Explanation:

The parts of an atom are:

- The crust: It is the outer part of the atom and is the place where the electrons are.

- The nucleus: It is the central part of the atom and is the place that contains the protons and neutrons.

The subatomic particles of the atom are:

- Electrons: They are negatively charged particles that go in the atom's crust and are divided into specific sections.

- Protons: They are particles with a positive electric charge, the number of protons in the nucleus of an atom is what determines the atomic number of an element.

- Neutrons: They are atoms with no electric charge.

Answer: React with the skin

Explanation:

lab safety test Safety goggles and an apron must be worn when handling chemicals labeled corrosive because they React with the skin

Answer:

A)0.00966 N/C

B) counterclockwise direction

Explanation:

We are given;

Diameter of the metal ring; d = 4.3 cm

Radius;r = 2.15 cm = 0.021- m

Initial magnetic field, B = 1.12 T

Rate of decrease of the magnetic field;dB/dt = 0.23 T/s

Now, as a result of change in magnetic field, an emf will be induced in it. Thus, , electric field is induced and given by the formula :

∫E•dr = d/dt∫B.A •dA

This gives;

E(2πr) = dB/dt(πr²)

Gives;. 2E = dB/dt(r)

E = dB/dt × 2r

We are given;

E = 0.23 × 2(0.021)

E = 0.00966 N/C

The magnitude of the electric field induced in the ring has a magnitude of 0.00966 N/C

B) The direction of electric field will be in a counterclock wise direction when viewed by someone on the south pole of the magnet

Explanation:

Given that,

Initial speed of the bus, u = 0

Acceleration of the bus, a = 0.5 m/s²

Let v is the velocity at the end of 2 minutes. The change in velocity divided by time equals acceleration.

So,

[tex]a=\dfrac{v-u}{t}\\\\v=u+at\\\\v=0+0.5\times 120\\\\v=60\ m/s[/tex]

Let d is the distance cover during that time. So,

[tex]v^2-u^2=2ad\\\\d=\dfrac{v^2-u^2}{2a}\\\\d=\dfrac{(60)^2}{2\times 0.5}\\\\d=3600\ m[/tex]

So, the final speed is 60 m/s and the distance covered during that time is 3600 m.

Answer:

Explanation:

a )

According to graph the object moves with constant velocity of 10 m /s during first 8 s and then its velocity changes to - 5 m /s from 8 th second upto 12 th second .

Initial displacement = 8 m

displacement during 8 s = velocity x time

= 8 x 10 = 80 m

total displacement = 88 m

b )

displacement during period from 8 th to 12 th s

= - 5 x 4 = - 20 m

total displacement after 12 s

= 88 - 20 = 68 m

c ) average speed = total distance covered during 12 s / total time

= (80 + 20) / 12

= 8.33 m /s

average velocity = total displacement during 12 s  / total time

= 80 - 20 / 12  

= 60 / 12

= 5 m /s .

[tex] \huge{ \underline{ \boxed{ \bf{ \blue{Solution:}}}}}[/tex]

We will solve the above Question by using equations of motion that are:-

Here,

By using first equation of motion,

⇛ v = u + at

⇛ 10 = 15 + a(2)

⇛ -5 = 2a

Flipping it,

⇛ 2a = -5

⇛ a = -2.5 m/s² [ANSWER]

❍ Acclearation is negative because final velocity is less than Initial velocity.

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Explanation:

Some Uses of Electromagnetic waves :

(A) Microwaves

(B) X - Rays (produced by slowing fast moving electrons)

(C) Radio Waves

Answer:

38.024 KWh

Explanation

250 watts multiplied with 5 hours daily multiplied with 28 days monthly equals 35000 Watt hours. Divided by a 1000 to get the KWh equals 35 KWh.

= 250×5hrs× 28days

= 35000watts

= 35000/1000

= 35KWh

Four 6 watt lightbulbs equals 24 watts 4x6=24

Hence, 24×4.5hrs×30days

= 3024watts

= 3024/1000

= 3.024KWhr

The total amount of energy consumed in the month of February = 35 KWh + 3.024 KWh = 38.024 KWh

Note that I had to use 28days since we are considering the month of February.

Answer:

7.2 seconds

Explanation:

50=5

72=t, criss-cross, t=72 (5)/50

Answer:

0.76 mg/s

Explanation:

0.46 kg/week × (1 week / 7 days) × (1 day / 24 hrs) × (1 hr / 3600 s) × (1000 g/kg) × (1000 mg/g) = 0.76 mg/s