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2 years ago

8. A car initially has 100 J of total energy. After driving down the road, the car's

Physics

1 answer:

sveta [45]2 years ago

8 0

The work done on the car is -20 J.

Work done on the car is negative, meaning that the car actually does work on the external system.

<h3>Energy and law of conservation of energy</h3>

Energy is the ability to do work
the law of conservation of energy states that the total energy in a system is conserved

From the law of conservation of energy, the initial energy of the car before it moves down the road remains constant or unchanged.

Initial energy = 100 J
Initial energy = Final energy - work done on car
Final Energy = Work done on car + initial energy

80J = Work done on car + 100 J

Work done on car = 80 - 100J

Work done on car = -20 J

Hence, the work done on the car is -20 J

Work done on car is negative.

Since work done on the car is negative, it means that the car actually does work on the external system. Hence, the decrease in the energy of the car.

Learn more about energy and work at: brainly.com/question/13387946

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Home Run

svp [43]

The force acting on the ball are unbalanced. Reactionary momentum force (that originated as a result of the swing of the bat) is the most powerful.

Yes friction is acting on the ball. In course of journey it would slow the ball down and make it trace a parabolic path rather than straight path as intended by hitter.

Explanation:

As the hitter hits the ball, momentum of the bat due to swing (mass of the bat*velocity provided by the batsman swinging action of bat) gets transferred on the ball on its impact with the bat.

Since ball’s mass is quite small as compared to the bat, the velocity of the ball increases by the same factor by which the ball’s mass is lower than the bat’s mass. This velocity causes forward motion of the ball (of course in the direction of bat’s motion, here the batsman intends to send the ball straight away hence the ball would move straight).

Various forces on ball is-

Reactionary momentum force -bat’s force (most powerful force)
The frictional force of the air (opposing the motion of the ball through the air)
Gravity force (pulling the ball down to the Earth)

As a combined effect of these force when all the force remains unbalanced, the ball moves away in the straight path under the impact of bats momentum which was most powerful of all.

Frictional force and Gravity force continue acting on the ball. While frictional forces decrease the ball velocity through the air, gravity force pulls it down thus deflecting its direction. Under the combined impact of declining bats momentum, friction force and gravity force, the ball traces a parabolic path (in accordance with the first law of motion from Newton)

8 0

3 years ago

5. Forces have

Verdich [7]

In physics, forces are interactions that are able to change the velocity of an object.

Force is a vector quantity, so it has a magnitude and a direction.

The SI units of the force is the Newton (N).

Whenever an unbalanced force is applied to an object, the object experiences an acceleration, according to Newton's second law of motion:

$F=ma$

where

F is the force

m is the mass of the object

a is its acceleration

So, the acceleration of an object is proportional to the force applied:

$a=\frac{F}{m}$

In physics, arrows are used to represent vector quantities. Therefore, they are also used to represent forces.

In particular, when a vector quantity is represented by an arrowr:

- The length of the arrow is proportional to the magnitude of the vector quantity

- The direction of the arrow corresponds to the direction of the vector quantity

Therefore, if a force is represented through an arrow:

- The length of the arrow shows the strength (magnitude) of the force

- The direction of the arrow shows the direction of the force

As we said in part 5), the SI units of the force is the Newton (N).

We can rewrite the Newton in terms of fundamental units only. We can do it starting from the equation:

$F=ma$

where

F is the force

m is the mass

a is the acceleration

- The mass is measured in kilograms (kg)

- The acceleration is measured in meters per second squared ( $m/s^2$ )

Therefore, 1 N corresponds to:

$[N]=[kg][\frac{m}{s^2}]=[kg\cdot m \cdot s^{-2}]$

Gravity is an attractive force that exists between all objects that have mass. See more explanations about gravity in part 4).

Mass is a scalar quantity; it gives us a measure of the "amount of matter" contained in an object.

The SI unit of the mass is the kilogram (kg).

Being a scalar, mass has no direction, but only a magnitude.

Moreover, the mass is an intrinsec property of an object: therefore, it does not depend on the location of the object. So, an object has always the same mass, either it is on Earth or on another planet.

On the other hand, the force of gravity on an object depends on its location, so it changes.

As we said in part 3), gravity is an attractive force that exists between all objects that have mass.

The magnitude of the force of gravity between two objects is given by the Universal Law of gravitation:

$F=\frac{Gm_1 m_2}{r^2}$

where

G is the gravitational constant

m1, m2 are the masses of the two objects

r is the separation between the objects

From the equation above, we observe that:

- all objects are attracted to one another with a gravitational force that is proportional to the mass of the objects and inversely proportional to the square of the distance between them.

And so:

a. When the mass of one or both objects increases, the gravitational force between the objects increases

b. When the distance between two objects increases, the attraction between the objects decreases

7 0

3 years ago

Vector A has y-component Ay= +15.0 m . A makes an angle of 32.0 counterclockwise from the +y-axis. What is the x component of A?

Gemiola [76]

Answer:

x-component=-9.3 m

Magnitude of A=17.7m

Explanation:

We are given that

$A_y=+15 m$

$\theta=32^{\circ}$

We have to find the x-component of A and magnitude of A.

According to question

$A_y=\mid A\mid cos\theta$

Substitute the values then we get

$15=\mid A\mid cos32$

$\mid A\mid =\frac{15}{cos32}=\frac{15}{0.848}$

$\mid A\mid=17.7$ m

$tan\theta=\frac{perpendicular\;side}{Base}$

$tan32=\frac{A_x}{A_y}=\frac{A_x}{15}$

$0.62\times 15=A_x$

$A_x=9.3$

The value of x-component of A is negative because the vector A lie in second quadrant.

Hence, the x- component of A=-9.3 m

6 0

3 years ago

Read 2 more answers

In transistor emitter current is equal to which current?

Paladinen [302]

In transistor,
Emitter current is equal to the sum of base current and collector current.
Thanks!

8 0

3 years ago

6. Draw conclusions: Newton’s first law states that an object in motion will travel at a constant velocity unless acted upon by

gavmur [86]

You can test if it’s true by holding a pencil in mid air over a table and the table is supposed to be the unbalanced forced that stopped the pencil from moving at the constant velocity it was going by.

5 0

3 years ago

Read 2 more answers