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3 years ago

A bird can fly 25 km/h. How long does it take to fly 3.5km?

1 answer:

7 0

Speed of bird = 25km / h, it means a bird covers a distance of 25 km in 1 hour or 60 minutes.
A birds covers a distance of 1 km in time = 1 hour = 60 min
so, 60 / 25 = 2.4 = 2 minutes 4 second
it means a bird covers a distance of 1 km in 2 minutes 4 second, so a bird take time to fly 3.5 km in time = 3.5 x 2.4 = 8.4 = 8 minutes 4 second
So, the answer is 8 minutes 4 seconds.

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8 POINTS AND BRAINIEST FOR CORRECT ANSWER

Fiesta28 [93]

The answer would be B. :)

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2 years ago

Ety ratio

horrorfan [7]

3) The work done is D. zero

4) The kinetic energy is B. 180 J

5) The potential energy is A. 120 J

6) The work done depends on B. position

7) The example of non-renewable energy is C. coal

8) The power expended is $3\cdot 10^4 W$

9) The efficiency is A. 100%

10) The velocity ratio is 5

Explanation:

The work done by a force acting an object is given by:

$W=Fd cos \theta$

where :

F is the magnitude of the force

d is the displacement

$\theta$ is the angle between the direction of the force and the displacement

When the force is applied perpendicular to the direction of motion,

$\theta=90^{\circ}$

Therefore, the work done is:

$W=Fd(cos 90^{\circ})=0$

The kinetic energy of a body is given by

$K=\frac{1}{2}mv^2$

where

m is the mass of the body

v is its speed

For the girl in this problem, we have

m = 40 kg

v = 3 m/s

Therefore her kinetic energy is

$K=\frac{1}{2}(40)(3)^2=180 J$

The potential energy of an object is given by

$PE=mgh$

where

m is the mass

$g=10 m/s^2$ is the acceleration of gravity

h is the heigth of the object relative to the ground

For the ball in this problem,

m = 0.4 kg

h = 30 m

So, the potential energy is

$PE=(0.4)(10)(30)=120 J$

A conservative field is a field for which the work done by the field on an object does not depend on the path taken, but only on the initial and final position of the object.

Gravitational and electric fields are examples of conservative fields. In fact:

When an object is pulled down by gravity (free fall), the work done by the gravitational field only depends on the change in height $\Delta h$ between the two points, not on the path taken during the fall
When an electric charge is pushed by the electric field, the work done by the field depends only on the initial and final position of the charge in the field

For any conservative field, it is possible to define a "potential" function, which represents the energy per unit mass/charge, and depends only on the position of the object.

Non-renewable energy sources are sources of energy whose rate of consumption is faster than the rate at which they are re-created. Examples of non-renewable sources are coal, oil, natural gas. These energy sources are consumed at a fast rate, while they take million of years to regenerate, so at the current rate they will eventually run out.
Renewable energy sources are sources of energy that replenish at faster rate than the rate at which it is consumed. Examples of renewable sources are solar energy, wind, hydroelectric power.

Therefore, the example of non-renewable energy in this case is

C. Coal

For an object pushed by a force F and moving at a constant velocity v, the power expended is given by

$P=Fv$

where F is the force and v is the velocity.

for the rocket in this problem, we have:

F = 10 N is the force propelling the rocket

v = 3000 m/s is its velocity

Substituting into the equation, we find the power expended:

$P=(10)(3000)=30,000 W = 3\cdot 10^4 W$

The efficiency of a machine is given by

$\eta = \frac{W_{out}}{W_{in}}$

where

$W_{in}$ is the energy in input to the machine

$W_{out}$ is the useful work in output from the machine

For a real machine, the useful work in output is always lower than the energy input, because part of the energy is "wasted" and converted into thermal energy due to the presence of internal frictions. However, for an ideal machine, all the input energy is converted into useful work, so

$W_{out}=W_{in}$

And therefore the efficiency is

$\eta=1$

which means 100%.

10.

The velocity ratio of a block and tackle system is the ratio between the distance moved by the effort and the distance moved by the load.

$VR=\frac{d_{eff}}{d_{load}}$

In a block and tackle system, the velocity ratio is also equal to the number of pulleys in the system.

For the system in the problem, there are 5 pulleys: therefore, this means that when the effort moves 5 metres, the load moves 1 metres, therefore the velocity ratio is

$VR=\frac{5}{1}=5$

Learn more about kinetic and potential energy:

brainly.com/question/6536722

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#LearnwithBrainly

5 0

3 years ago

Using a 683 nm wavelength laser, you form the diffraction pattern of a 1.1 mm wide slit on a screen. You measure on the screen t

n200080 [17]

Answer:

10.2 m

Explanation:

The position of the dark fringes (destructive interference) formed on a distant screen in the interference pattern produced by diffraction from a single slit are given by the formula:

$y=\frac{\lambda (m+\frac{1}{2})D}{d}$

where

y is the position of the m-th minimum

m is the order of the minimum

D is the distance of the screen from the slit

d is the width of the slit

$\lambda$ is the wavelength of the light used

In this problem we have:

$\lambda=683 nm = 683\cdot 10^{-9} m$ is the wavelength of the light

$d=1.1 mm = 0.0011 m$ is the width of the slit

m = 13 is the order of the minimum

$y=8.57 cm = 0.0857 m$ is the distance of the 13th dark fringe from the central maximum

Solving for D, we find the distance of the screen from the slit:

$D=\frac{yd}{\lambda(m+\frac{1}{2})}=\frac{(0.0857)(0.0011)}{(683\cdot 10^{-9})(13+\frac{1}{2})}=10.2 m$

6 0

3 years ago

A box of paper is labeled 24lb paper. This means that 500 sheets (counted number) of paper size 17in x 22in weighs 24 pounds (Th

Tresset [83]

Answer:

The mass of a single paper is approximately 0.047 lb/paper which in SI Units is approximately 21.77 g/paper

Explanation:

The given information on the size and the weight of paper are;

The mass of a box of 500 sheets of paper = 24 lb

The number of sheets in the paper = 500 sheets

The dimensions of the paper = 17 in. × 22 in., which is equivalent to 43.18 cm × 55.88 cm

The mass of a single paper = The mass of the box of paper/(The number of sheets of paper present in the box)

The mass of a single paper = 24 lb/500 = 0.047 lb/paper

Given that 1 lb = 453.6 g, we have;

0.047 lb/paper = 0.047 lb/paper×453.6 g/(lb) = 21.77 g/paper

The mass of a single paper = 0.047 lb/paper = 21.77 g/paper.

6 0

3 years ago

What is the difference between compound, element and mixture?

defon

Compound; consists of atoms of two or more different elements bound together,can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means) has properties that are different from its component elements, and always contains the same ratio of its component atoms.Mixtures; Note that a mixture:consists of two or more different elements and/or compounds physically intermingled, can be separated into its components by physical means, and often retains many of the properties of its components.

4 0

3 years ago