Conditional waves contain a crest, trough, wavelength, and amplitude<br> True or False?

The electric current in a wire is 1.5A. How many electrons flow past a given point in a time of 2s?

kipiarov [429]

Answer:

The amount of electrons that flow in the given time is 3.0 C.

Explanation:

An electric current is defined as the ratio of the quantity of charge flowing through a conductor to the time taken.

i.e I = $\frac{Q}{t}$ ...................(1)

It is measure in Amperes and can be measured in the laboratory by the use of an ammeter.

In the given question, I = 1.5A, t = 2s, find Q.

From equation 1,

Q = I × t

= 1.5 × 2

= 3.0 Coulombs

The amount of electrons that flow in the given time is 3.0 C.

5 0

2 years ago

Gravitational notes of physics

Pachacha [2.7K]

Answer:

Every object in the universe attracts other object by a force of attraction, called gravitation, which is directly proportional to the product of masses of the objects and inversely proportional to the square of distance between them. This is called Law of Gravitation or Universal Law of Gravitation.

Let masses (M) and (m) of two objects are distance (d) apart. Let F be the attractional force between two masses.

Importance of The Universal Law of Gravitation

It binds us to the earth.

It is responsible for the motion of the moon around the earth.

It is responsible for the motion of planets around the Sun.

Gravitational force of moon causes tides in seas on earth.

Free Fall

When an object falls from any height under the influence of gravitational force only, it is known as free fall.

Acceleration Due to Gravity

When an object falls towards the earth there is a change in its acceleration due to the gravitational force of the earth. So this acceleration is called acceleration due to gravity.

The acceleration due to gravity is denoted by g.

The unit of g is same as the unit of acceleration, i.e., ms−2

Mathematical Expression for g

From the second law of motion, force is the product of mass and acceleration.

F = ma

For free fall, acceleration is replaced by acceleration due to gravity.

Therefore, force becomes:

F = mg ….(i)

But from Universal Law of Gravitation,

Factors Affecting the Value of g

As the radius of the earth increases from the poles to the equator, the value of g becomes greater at the poles than at the equator.

As we go at large heights, value of g decreases.

To Calculate the Value of g

Value of universal gravitational constant, G = 6.7 × 10–11 N m2/ kg2,

Mass of the earth, M = 6 × 1024 kg, and

Radius of the earth, R = 6.4 × 106 m

Putting all these values in equation (iii), we get:

Thus, the value of acceleration due to gravity of the earth, g = 9.8 m/s2.

Difference between Gravitation Constant (G) and Gravitational Acceleration (g)

S. No.

Gravitation Constant (G)

Gravitational acceleration (g)

1.

Its value is 6.67×10-11Nm2/kg2.

Its value is 9.8 m/s2.

2.

It is a scalar quantity.

It is a vactor quantity.

3.

Its value remains constant always and everywhere.

Its value varies at various places.

4.

Its unit is Nm2/kg2.

Its unit is m/s2.

Motion of Objects Under the Influence of Gravitational Force of the Earth

Let an object is falling towards earth with initial velocity u. Let its velocity, under the effect of gravitational acceleration g, changes to v after covering the height h in time t.

Then the three equations of motion can be represented as:

Velocity (v) after t seconds, v = u + ght

Height covered in t seconds, h = ut + ½gt2

Relation between v and u excluding t, v2 = u2 + 2gh

The value of g is taken as positive in case of the object is moving towards earth and taken as negative in case of the object is thrown in opposite direction of the earth.

Mass & weight

Mass (m)

The mass of a body is the quantity of matter contained in it.

Mass is a scalar quantity which has only magnitude but no direction.

Mass of a body always remains constant and does not change from place to place.

SI unit of mass is kilogram (kg).

Mass of a body can never be zero.

Weight (W)

The force with which an object is attracted towards the centre of the earth, is called the weight of the object.

Now, Force = m × a

But in case of earth, a = g

∴ F = m × g

But the force of attraction of earth on an object is called its weight (W).

∴ W = mg

As weight always acts vertically downwards, therefore, weight has both magnitude and direction and thus it is a vector quantity.

The weight of a body changes from place to place, depending on mass of object.

The SI unit of weight is Newton.

Weight of the object becomes zero if g is zero.

Weight of an Object on the Surface of Moon

Mass of an object is same on earth as well as on moon. But weight is different.

Weight of an object is given as,

Hence, weight of the object on the moon = (1/6) × its weight on the earth.

Try the following questions:

Q1. State the universal law of gravitation.

Q2. When we move from the poles to the equator, the value of g decreases. Why?

Q3. If two stones of 150 gm and 500 gm are dropped from a height, which stone will reach the surface of the earth first and why ?

Q4. Differentiate between weight and mass.

Q5. Why is the weight of an object on the moon 1/6th its weight on the earth??

7 0

3 years ago

How much work does the electric field do in moving a proton from a point with a potential of +125 v to a point where it is -55 v

777dan777 [17]

The work W done by the electric field in moving the proton is equal to the difference in electric potential energy of the proton between its initial location and its final location, therefore:
$W= qV_i - qV_f$
where q is the charge of the proton, $q=1 e = 1.6\cdot 10^{-19}C$ , with $e$ being the elementary charge, and $V_i = +125 V$ and $V_f = -55 V$ are the initial and final voltage.

Substituting, we get (in electronvolts):
$W=e(125 V-(-55 V))=180 eV$
and in Joule:
$W=(1.6 \cdot 10^{-19})(125 V-(-55V))=2.88 \cdot 10^{-17}J$

5 0

3 years ago

Star A and Star B have measured stellar parallax of 1.0 arc second and 0.75 arc second, respectively. Which star is closer? How

zhuklara [117]

Answer:

Star A is closer than Star B

Explanation:

As we know that in parallax method of distance measurement the angle subtended by the star when it covers a distance of one Parsec arc length, it is known as parallax angle

Here we can say

$angle = \frac{1 Parsec}{distance}$

so we have

$distance = \frac{1 Parsec}{angle}$

so here we have

angle subtended by Star A = 1 arc sec

angle subtended by star B = 0.75 arc sec

now we have

distance for star A is given as

$d_a = \frac{1 Parsec}{1} = 1 Parsec$

distance of star B is given as

$d_b = \frac{1 Parsec}{0.75} = 1.33 Parsec$

So star A is closer than star B

7 0

3 years ago

Why is Pluto now called a dwarf planet

zvonat [6]

Before Pluto was discovered, it was predicted. Astronomers had observed that massive objects can affect the orbits of its neighbors, and, after seeing deviations in the orbits of Uranus and Neptune, assumed something substantial existed beyond their orbits.
When Pluto was spotted, it was thought to be the predicted object and was identified as a ninth planet.
A few decades later, astronomers started discovering more and more objects around other stars and didn’t know whether to call them planets or not. There appeared to be a need to define what a planet means, and that led to what some people consider Pluto’s demotion to a dwarf planet.
The International Astronomical Union decided that full-sized planets must orbit the sun, have a round shape, and have cleared their orbits of other objects. Pluto fulfills the first two criteria, but not the third.
It still goes around the sun, it’s round enough, it’s got moons, and behaves like a planet, but the idea is that Pluto did not form the same way as the rest of the planets. Pluto’s orbit is both eccentric and inclined more than the rest of the planets by about 17 degrees. That’s suggests something is different about this object.
This debate about whether to call it a planet or not is silly, because it doesn’t matter to Pluto what you call it. It is an interesting object, goes around the sun, and shows geology and an atmosphere.
There’s a tendency to define objects based on what they are now, but nothing is constant in the universe. There are some issues with the nomenclature, and a definition today may not apply to the same object tomorrow.

7 0

3 years ago

Read 2 more answers

Conditional waves contain a crest, trough, wavelength, and amplitude True or False?​

Conditional waves contain a crest, trough, wavelength, and amplitude True or False?