Could someone tell me if this is right or give me the answers so i can re write them! That would be so helpful:)

Answer:

The man has, at most, 0.4 secs to get out of the way

Explanation:

First, we will determine, the time the block takes to reach height 13.4 m above the ground.

Also, we will determine the time it will take to reach the man, if he does not notice it.

Then, the difference in the two times will be the time the man has to get out of the way.

From the formula

[tex]h =ut - \frac{1}{2}gt^{2}[/tex]

Where [tex]h[/tex] is height

[tex]u[/tex] is the initial velocity

[tex]t[/tex] is time

and [tex]g[/tex] is acceleration due to gravity ( Take [tex]g =[/tex] 9.8 m/s²)

Let the time the block takes to reach height 13.4 m be [tex]t_{1}[/tex]

The cement block falls from a 51.1 m high building, then by the time it reaches a height 13.4 m above the ground, the displacement is

13.4 m - 51.1 m = - 37.7 m  

The is the height the block has fallen from by the time it gets to a height 13.4 m above the ground

Then,  

[tex]h =ut - \frac{1}{2}gt^{2}[/tex]

[tex]-37.7 = (0)(t_{1}) - \frac{1}{2}(9.8)t_{1}^{2}[/tex]

(NOTE: [tex]u[/tex] = 0 m/s because the cement block falls from rest)

[tex]37.7 = 4.9t_{1}^{2}[/tex]

[tex]t_{1}^{2}= \frac{37.7}{4.9}[/tex]

[tex]t_{1}= \sqrt{7.69} \\[/tex]

[tex]t_{1}= 2.77 secs[/tex]

Hence, It takes the block 2.77 secs to reach height 13.4 m

Also,

Let the time it will take to reach the man be [tex]t_{2}[/tex]

The man is 1.70 m tall, hence, to reach the man, the cement block would have reached a height ( 1.70 m - 51.1 m) = - 49.4 m

Then,

[tex]h =ut - \frac{1}{2}gt^{2}[/tex]

[tex]-49.4 = (0)(t_{2}) - \frac{1}{2}(9.8)t_{2}^{2}[/tex]

[tex]49.4 = 4.9t_{2}^{2}[/tex]

[tex]t_{2}^{2} = \frac{49.4}{4.9}[/tex]

[tex]t_{2}= \sqrt{10.08}[/tex]

[tex]t_{2}= 3.17 secs[/tex]

Hence, it will take 3.17 secs to reach the man

Now, for the time the man has to get out of the way, that is

[tex]t_{2} - t_{1}[/tex] = 3.17 secs - 2.77 secs

= 0.4 secs

Hence, the man has, at most, 0.4 secs to get out of the way

Answer:

Three forms of energy when a match is being lit are potential, kinetic and thermal.

hope this helps! :)

Explanation:

Answer:

Potential Energy

Kinetic Energy

Thermal Energy

Explanation:

Answer:

13 hours, 16 minutes, 41 seconds

Explanation:

Distance of Saturn from the Sun

= 890,700,000 miles

[tex] = 8.907\times 10^8 \: miles\\

= 8.907\times 10^8 \times 1.61 \times 10^3 \:meters\\

= 14.34027\times 10^{11}\: m\\

= 1. 434027\times 10^{12}\: m\\\\

\because Time = \frac{Distance}{Speed} \\

\therefore Time = \frac{1.434027\times 10^{12}}{3\times 10^8}\\

\therefore Time = 4.78009 \times 10^{12-8}\\

\therefore Time = 4.78009 \times 10^{4} \:seconds \\

\therefore Time = 47800.9 \:seconds\\

\therefore Time = 47801 \:seconds\\

\therefore Time = 13h\: 16m\: 41s\\[/tex]

Saturn is 890,700,000 miles from the Sun. This distance in the scientific notation would be 1.434×10¹² metes.

If the speed of light is 3.0 x 108 meters/second, then it would take 4780 seconds for light from the Sun to reach Saturn.

The total displacement covered by any object per unit of time is known as velocity. It depends on the magnitude as well as the direction of the moving object. The unit of velocity is meter/second. It can also be represented by the infinitesimal rate of change of displacement with respect to time. The generally considered unit for velocity is a meter per second.

As given in the problem Saturn is 890,700,000 miles from the Sun

1 mile = 1.61 x 10³ meters

890,700,000 miles = 890,700,000×1.61×10³ meters

                                =1.434×10¹² metes

As given  If the speed of light is 3.0 x 10⁸ meters/second

Time = distance /speed

        = 1.434×10¹² metes / 3.0 x 10⁸ meters/second

        = 4780 seconds

Thus, the distance in the scientific notation would be 1.434×10¹² metes and it would take 4780 seconds for light from the Sun to reach Saturn.

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Answer:

Yes, at the highest point in the trajectory velocity and acceleration are perpendicular.

Explanation:

Let [tex]x-[/tex]axis be the ground and [tex]y-[/tex]axis is the height above the ground. Let the initial velocity of the object is [tex]u[/tex] having angle [tex]\theta[/tex] with respect to ground and the acceleration due to gravity , [tex]g[/tex], is acting in vertically downward direction as shown in figure.

As gravitational force is acting in vertical direction, so, it will not change the horizontal velocity of the object. So, at any instant throughout the projectile motion the [tex]x-[/tex]component of the initial velocity will remailns constant, i.e. [tex]u_x=u \cos \theta[/tex].

While, due gravitational force, [tex]y-[/tex]component of the initial velocity will change. Initially, [tex]u_y=u \sin \theta[/tex] is in vertically upward direction and gravitational force is actiongn vertically downward direction, so, at first [tex]u_y[/tex] will decrease untill it reaches the highest point of the trajectory as shown. At the highest point the vertical component of the velocity [tex]u_y=0[/tex], so, there is only horizontal component of the velocity. i.e [tex]u_x= u \cos\theta[/tex] .

Now, the resultant velocity of the object at the highest point is [tex]u \cos \theta[/tex] which is in the horizontal direction while the acceleration , [tex]g[/tex] , (due to gravily) is actiog in vertically downward direction.

Hence, at the highest point in the trajectory velocity and acceleration are perpendicular.

Thus the response above is appropriate.

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Answer:

A.) 1.81 m/s

B.) 16.07 m/s

C.) 6.88 degree.

Explanation:

Given that Inside, two siblings 1.90 m apart are playing catch directly across the aisle. The kid wearing a Catherine Wheel T-shirt throws the ball horizontally north. The ball crosses the train and is caught 1.05 s later by her little brother.

The velocity of the ball will be

Velocity = displacement/ time

Where displacement = 1.90 m

Time = 1.05 s

Velocity = 1.9 / 1.05

Velocity = 1.8095

Velocity = 1.81 m/s

A.) From the little brother point of view, the magnitude of ball's velocity will be 1.81 m/s

B.) The magnitude of the velocity of the ball as seen by someone standing still outside the train will be achieved by first converting km/h to m/s

(54 × 1000) / 3600 = 15 m/s

Then, use pythagorean theorem to find the velocity

V = sqrt ( 15^2 + 1.81^2)

V = sqrt ( 225 + 3.2761)

V = sqrt ( 258.2761)

V = 16.07 m/s

C.) The angle will be

Tan Ø = 1.81 / 15

Tan Ø = 0.1206666

Ø = tan^-1(0. 1206666)

Ø = 6.88 degree.

Complete Question

The  complete question is shown on the first uploaded image

Answer:

the compass direction of the resultant displacement is  [tex]\theta  =4.7^o [/tex] south of west

Explanation:

Generally using cosine we can obtain the resultant R as follows

     [tex]R^2  =  A^2  + B^2 -2ABcos(70)[/tex]

=>   [tex]R  =  \sqrt{12^2  + 20^2  - 2(12 ) *  (20) cos  70}[/tex]

=>    [tex]R  =  19.48 \  m[/tex]

We can obtain the direction of the resultant by first  using sine rule to obtain angle C as follows

       [tex]\frac{A}{sin  C}  =  \frac{R}{sin70 }[/tex]

=>    [tex]C=  sin ^{-1} [\frac{A *  (sin 70)}{R} ][/tex]

=>    [tex]C =  sin ^{-1} [\frac{20 *  (sin 70)}{19.48} ][/tex]

=>  [tex]C =  74.7 ^o[/tex]

Then the direction is obtained as

       [tex]\theta  =  C  -  70[/tex]

=>    [tex]\theta  = 74.7   -  70[/tex]

=>     [tex]\theta  =4.7^o [/tex]

Hence the compass direction of the resultant displacement is  [tex]\theta  =4.7^o [/tex] south of west

Answer:

800 miles per hour

Explanation:

Answer:

a) compresses and warms.

Explanation:

When air sinks, it falls down and compresses the air close to the surface of the ground, which raises the temperature of the air (since compression results in a rise in temperature). Also, as the air sinks, it prevent the already warm air close to the surface from rising, further increasing its own temperature, warming it up.

Answer:

Yes the answer is A.)  A Nucleus

Explanation:

I took the test

Rutherford’s model of the atom included a nucleus  that Thomson’s model did not have, therefore the correct option is A

There are some models that are used to explain the arrangements of subatomic particles inside the atom based on the atomic theory of atom are known as the atomic models.

There are many types of atomic models proposed in past based on their individual assumptions and the experimentations

There are mainly five most widely accepted atomic models

John Dalton's atomic model which based on the assumption that all the entities of the universe are made up of the fundamental particle that is an atom.

J.J. Thomson's model: Plum Pudding model explains the arrangement of subatomic particles by taking the example of plum pudding in which positive charge is distributed uniformly throughout and the negative charge particles are sprinkled on it in a random fashion.

Rutherford's model explained the existence of a nucleus inside the atom by using the alpha particle bombardment experiment on a thin sheet of gold.

Niels Bohr's model explained the revolving nature of the electrons in the different shells around the nucleus of the atom.

Erwin Schrodinger's model explains the arrangement of the subatomic particles as the electron Cloud Model also known as the Quantum Model.

Rutherford’s model of the atom included a nucleus  that Thomson’s model did not have, therefore the correct option is A

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Explanation:

Given:

v₀ = 15.68 m/s

a = -9.8 m/s²

t = 0.4n s, n = 0, 1, 2, etc.

Find: Δy and v

To find displacement, use the equation:

Δy = v₀ t + ½ at²

To find velocity, use the equation:

v = at + v₀

[tex]\left\begin{array}{ccc}t&y&v\\0&0&15.68\\0.4&5.49&11.76\\0.8&9.41&7.84\\1.2&11.76&3.92\\1.6&12.54&0\\2.0&11.76&-3.92\\2.4&9.41&-7.84\\2.8&5.49&-11.76\\3.2&0&-15.68\end{array}\right[/tex]

The ball lands after 3.2 seconds.

Answer:

calculated velocities:

(t,v(t))

(0.4,11.756)

(0.8,7.832)

(1.2,3.908)

(1.6,-0.016)

calculated displacements:

[tex](t,\Delta x)[/tex]

(0.4, 5.487)

(0.8,9.4048)

(1.2, 11.7528)

(1.6, 12.5312)

the ball spends 3.2 seconds in the air

Explanation:

Assuming the ball is launched on earth with standard gravity and that the effects of drag is neglected.

assume that 'up' is positive direciton since that is direction of travel

'down' is negative direction

formula for velocity is [tex]v(t)=v_0+at[/tex]

where [tex]v(t)[/tex] is the velocity at time [tex]t[/tex]

[tex]v_0[/tex] is the initial velocity at time [tex]t=0[/tex]

[tex]a[/tex] is the acceleration in the direction of the velocity

velocity is in m/s and accelration is in m/s^2 and t is in seconds

for displacement: [tex]\Delta x=v_0 t+\frac{1}{2}at^2[/tex]

Known stuffs:

in our case, we know we are on earth so, [tex]a=-9.81[/tex]m/s^2. the negative sign indicates that the direction is oposite the velocity since the ball travels up but gravity pulls down

the initial velocity is given as [tex]v_0=15.68[/tex]m/s

therefore, our equation for velocity is

[tex]v(x)=15.68-9.81t[/tex]

now we just need to plot it every 0.4 seconds

this is easy subsituteion. here's the first:

[tex]v(0.4)=15.68-9.81(0.4)=11.756[/tex]m/s

if we keep plotting this, we get the following table

(t,v(t))

(0.4,11.756)

(0.8,7.832)

(1.2,3.908)

(1.6,-0.016) the velocity is negative meaning that the ball is now going 'down' and therefor the ball has just passed the peak of it's upward travel

so since it took about 1.6 seconds to get here, it will spend about twice this time in the air or about 3.2 seconds

to get an exact answer, solve for the time when velocity is 0, ie when the ball has reached its peak and stopped moving

set [tex]v(t)=0[/tex] and solve for t

[tex]0=15.68-9.81t\rightarrow 15.68=9.81t\rightarrow t=1.598s[/tex]

so it takes 1.598 seconds to get to peak, therefore it spends twice this time in the air or 3.197 seconds in the air. it's close enough to 3.2 seconds

the ball spends 3.2 seconds in the air

displacement:

[tex]\Delta x=v_0t+\frac{1}{2}at^2[/tex]

[tex]\Delta x=15.68t+\frac{1}{2}(-9.81)t^2[/tex]

some values are

[tex](t,\Delta x)[/tex]

(0.4, 5.487)

(0.8,9.4048)

(1.2, 11.7528)

(1.6, 12.5312)

Answer:

An applied force is a force that is applied to an object by a person or another object. If a person is pushing a desk across the room, then there is an applied force acting upon the object.

Explanation:

Answer:

Explanation:

Given the capacitance of a capacitor = 8.5F

Voltage across the capacitor = 2te^-3tV

The current across a capacitor is expresses as shown;

I = Cdv/dt

Given V = 2te^-3tV

dv/dt = 2t(-3e^-3t) + 2(e^-3t)

dv/dt = -6te^-3t + 2e^-3t

Factor out the common term

dv/dt = -2e^-3t{3t-1}

If C = 8.5F

I = 8.5 × -2e^-3t{3t-1}

I = -17.0e^-3t{3t-1} A

Power is the product of current and voltage.

P = IV

Given I = -17.0e^-3t{3t-1} A

V = 2te^-3t V

Power = -17.0e^-3t{3t-1} × 2te^-3t

Power = (17e^-3t - 51te^-3t) × 2te^-3t

Power = 34te^{-3t-3t} - 102t²e^{-3t-3t}

Power = 34te^-6t - 102t²e^-6t

Power = 34te^-6t{1-3t} Watts

Answer:

A

Explanation:

Answer:

26.64 m

Explanation:

Given the following :

Acceleration at ocean surface = 0.0800 m/s²

Distance covered if initial speed = 0.700 m/s and accelerates to a speed of 2.18m/s

Using the equation :

v² = u² + 2as

Where ;

v = final velocity ; u = initial velocity ; a = acceleration ; s = distance covered

Therefore,

v² = u² + 2as

2.18² = 0.7² + (2 × 0.08 × s)

4.7524 = 0.49 + 0.16s

4.7524 - 0.49 = 0.16s

4.2624 = 0.16s

s = 4.2624 / 0.16

s = 26.64 m

Explanation:

The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.

hope it helps

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Answer:

a = 1.16 m/s²

Explanation:

In order to find the rate of acceleration of the ball, we will use third equation of motion, as follows:

2as = Vf² - Vi²

where,

a = rate of acceleration = ?

s = distance covered by the ball = 21.9 m

Vf = Final Velocity of the ball = 7.14 m/s

Vi = Initial Velocity of the ball = 0 m/s (Since, the ball started from rest)

Therefore,

2(a)(21.9 m) = (7.14 m/s)² - (0 m/s)²

a = (50.97 m²/s²)/(43.8 m)

a = 1.16 m/s²

Answer:

I think it would be interviewing the researchers I'm unsure though

Answer:

Probably C) Conducting the experiment again

Explanation:

Option A is wrong because there is a chance that the group of researchers made a mistake or got the wrong data. So when interviewing the researchers, there is a chance of them giving the wrong data, especially since the experiment has never been conducted before.

Option B is wrong because the experiment the researchers where doing was new and has never been conducted before. Therefore there is no older research done on that topic.

Option C is correct because when conducted the experiment again, they can compare their results with the group of researchers. Checking if the data is correct.

Option D is wrong because the group of researchers might have made a mistake when writing down the procedure, leading to false data.

Given :

Mass of box , m = 250 kg.

Force applied , F = 285 N.

The value of the incline angle is 30°.

the coefficient of dynamic friction is [tex]\mu=0.72[/tex] .

To Find :

The speed with which the box is moving with, assuming it takes 4 seconds to reach the top of the incline.

Solution :

Net force applied in box is :

[tex]F=285 - mgsin\ \theta - \mu mg cos \ \theta\\ \\F=285-mg( sin \ \theta - \mu cos\ \theta)\\\\F=285 - 20\times 10( \dfrac{1}{2}+0.72\times \dfrac{\sqrt{3}}{2})\\\\F=60.29\ N[/tex]

Acceleration , [tex]a=\dfrac{F}{m}=\dfrac{60.29}{20}=3.01\ m/s^2[/tex].

By equation of motion :

[tex]v=u+at\\\\v=0+3.01\times 4\\\\v=12.04\ m/s[/tex]

Therefore, the speed of box is 12.04 m/s.

Hence, this is the required solution.  

Answer:

Efficiency Or C. on e2020

The ratio of output work to input work of a machine expressed as a percent refers to efficiency of the machine.

How well a machine converts its input energy into useable output energy, or work, is referred to as its efficiency. It is the portion or percentage of the output divided by the input, and it plays a significant role in a machine's utility.

It denotes the degree of performance that requires the fewest inputs to provide the greatest amount of output in more mathematical or scientific words. It frequently particularly refers to the ability of a particular application of effort to deliver a particular output with the least amount of waste, expense, or superfluous work. Efficiency covers a wide range of inputs and outputs across numerous disciplines and sectors.

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Answer:

V = (5.8cm/s)i, (4.7cm/s)j

Explanation:

Given :

r⃗ =[ 4.50 cm +( 2.90 cm/s2 )t2]i^+( 4.70 cm/s )tj^

To obtain the average velocity (V)

V = (r2 - r1) / (t2 - t1)

To obtain r1 and r2, substitute t1 = 0 and t2 = 2 respectively in the equation above

r1 = [ 4.50 cm +( 2.90 cm/s2 ) 0]i^+( 4.70 cm/s )0 j

r1 = 4.50 cm + 0 + 0 = (4.50cm)i + 0j

r2 = [ 4.50 cm +( 2.90 cm/s2 )2²]i^+( 4.70 cm/s )2 j

r2 = 4.50cm + (2.90 × 4)i + (4.70 × 2)j

r2 = (16.1cm)i + (9.4cm)j

V = [(16.1 - 4.50)i - (9.4 - 0)j] / 2 - 0

V = 11.6i / 2 ; 9.4j / 2

V = (5.8cm/s)i, (4.7cm/s)j

Answer:

stable is the answer

Explanation:

stable electrons

Answer:

hola bb como estas dime bb en que te ayudo

Explanation:

Answer:

Explanation:

According to Newton's first law of motion "An object will continue to stay or remain at rest or continue to be in constant motion "unless acted upon by an external force"

F= ma

Basically a force is a pull or a push

so in other words the two ways by which an object can get in motion is by

1. A pull force

2. A push force

Answer:

93.615 million or more

Explanation:

The Sun is about 93 million miles from Earth to calculate the distance to a star, astronomers observe it from different places along Earth's orbit around the Sun.

Answer:

Explanation:

An atom is said to be electrically neutral, if the said atom contains equal or the same numbers of protons and electrons.

Worthy of note is that most bodies are normally close to being electrically neutral. This is because of the number of electrons on the body being equal to the number of protons on the same body. Charging a body means one would have to transfer electric charge to the body, or from the body. As a result, the number of electrons in the body will no longer be equal to the number of protons on the body.

Answer:

35.625° C

Explanation:

See attachment

a) Final temperature is 35.625° C

b) 0°