During a race, a sprinter increases from 5.0 m/s to 7.5 m/s over a period of 1.25s. What is the sprinter’s average acceleration during this period?

Answer:

(a) -6.67 [tex]m/s^2[/tex]

(b) 0.68

Explanation:

Given that the mass of the truck, [tex]m_1=8000[/tex] kg.

Mass of the package, [tex]m_2=3000[/tex] kg.

As the package does not slide, so the acceleration of both, truck as well as the package, is the same.

Let [tex]a\;\; m/s^2[/tex] is the acceleration of the combined mass, m.

[tex]m=m_1+m_2= 8000+3000=11000[/tex] kg.

The initial velocity of the combined mass, u= 20 m/s.

Time required to stop, t=3 seconds.

Final velocity, v=0.

Displacement traveled, s=50 m.

(a) As  [tex]a=\frac {v-u}{t}[/tex]

[tex]\Rightarrow a=\frac{0-20}{3}=-\frac{20}{3} =6.67 m/s^2[/tex]

Hence the acceleration of the truck is [tex]-6.67 m/s^2.[/tex]

(b) Now, [tex]a=-6.67 m/s^2[/tex] is the acceleration of the package, this acceleration is due the frictional force, f.

Due to inertia, on application of break, the package have tendency to slide to left (in  the direction of velocity). But the package does not slides, this is only due to the frictional force, f, which acts in the right direction ( opposite to the direction of velocity).

So, the magnitude of frictional force required on [tex]m_2[/tex]  to avoid slide is

[tex]f=|m_2a|=\frac{20}{3}m_2\times(i)[/tex]

Now, let \mu be the minimum coefficient of the friction, so

The force due to friction, [tex]f_r= \mu N[/tex],

where [tex]\mu N[/tex] is the normal reaction.

[tex]N=m_2g[/tex], where g is the acceleration due to gravity.

So, [tex]f_r=\mu m_2g\cdots(ii)[/tex]

To avoid slide, [tex]f_r\geq f[/tex]

[tex]\Rightarrow \mu m_2g\geq\frac{20}{3}m_2[/tex] [from (i)and (ii)]

[tex]\Rightarrow \mu\geq \frac{20}{3\times 9.81}[/tex]    [tex][ as \;g=9.81 m/s^2][/tex]

[tex]\Rightarrow \mu \geq 0.68[/tex]

Hence, the minimum value of coefficient of friction between packages and the truck os 0.68.

Answer: I'm sure the answer is a.

Explanation: I hope that helped you.

Answer:

Precipitate

Explanation:

Answer:

This is what I got the teacher hasn’t graded it yet so sorry if it’s not right

Explanation:

Answer:

Rt = 908.25 [ohm]

Explanation:

In order to solve this problem, we must remember that the resistors connected in series are added up arithmetically.

In this case, R2 and R3 are in series therefore.

R₂₃ = 200 + 470

R₂₃ = 670 [ohm]

Now this new resistor (R₂₃) is connected in parallel with the resistor R4. therefore we must use the following arithmetic expression, to add resistances in parallel.

[tex]\frac{1}{R_{4-23} }= \frac{1}{R_{4}}+\frac{1}{R_{23} } \\\frac{1}{R_{4-23} }=\frac{1}{1800}+\frac{1}{670} \\R_{4-23}=488.25[ohm][/tex]

In this way R₁, R₅ and R₄₋₂₃ are connected in series.

Rt = R₁ + R₅ + R₄₋₂₃

Rt = 150 + 270 + 488.25

Rt = 908.25 [ohm]

Answer:

I believe gravity is acting on it

Answer: B. The speed will decrease.

Explanation:

When you ride a roller coaster, the wheels rub/scrape the rails, creating heat as a result of friction. And friction will slow you down. So increasing the friction on a roller coaster would slow it down.

Answer:

B

Explanation:

Friction opposes motion therefore reducing motion

Answer:

Eh = 21 [J]

Removed as heat.

Explanation:

This is a case of energy conservation, we have to take into account the energies that go in and out of the system. In this case, 135 [J] of energy are entered in the form of work of the compressor to the chamber where the refrigerant is compressed, now of these 135 [J] 114 [J] were used as internal energy, this internal energy is used to increase the pressure and temperature of the refrigerant.

In this way the rest of the energy of the 135 [J] was lost in the form of heat to determine this loss of energy, we simply perform the arithmetic subtraction.

Eh = 135 - 114 = 21 [J]

Eh = 21 [J]

Answer:

C.) the mass of mars is less than the mass of earth.

Explanation:

The more mass of the planet, the stronger the gravitational pull is. The rover will seem lighter on mars because there is less gravity pulling it onto the planet.

The mass of mars is less than the mass of earth.

The more mass of the planet, the stronger the gravitational pull is. The rover will seem lighter on mars because there is less gravity pulling it onto the planet.

Earth, the third planet from the Sun, is the planet where all known life is found. Although the Solar System contains enormous amounts of water, only Earth is home to liquid surface water.

The ocean covers roughly 70.8% of Earth's surface, dwarfing the polar ice, lakes, and rivers. Earth's surface is made up of continents and islands for the remaining 29.2% of its total area.

Therefore, The mass of mars is less than the mass of earth.

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Answer:

Candle

Explanation:

The moon is an illuminated object, while a candle is a luminous object!

Answer:

Candle

Explanation:

I just took the test

Answer:

a) [tex] y_{max} = 7.7 m [/tex]

b) y = 7.4 m

Explanation:

a) La altura máxima que alcanza la pelota se puede encontrar usando la siguiente ecuación:

[tex] y_{max} = y_{0} + v_{0y}t - \frac{1}{2}gt^{2} [/tex]    (1)

En donde:  

[tex]y_{0}[/tex]: es la altura inicial = 0

[tex]v_{0y}[/tex]: es la velocidad inicial en y

g: es la gravedad = 9.81 m/s²

t: es el tiempo

Primero debemos encontrar la velocidad inicial en y:

[tex] v_{fy} = v_{0y} - gt [/tex]

Sabiendo que la velocidad final en y es igual a cero (en la altura máxima), y con t = 1.25 s (la mitad del tiempo total) tenemos:

[tex] v_{0y} = gt = 9.81 m/s^{2}*1.25 s = 12.3 m/s [/tex]

Ahora, podemos encontrar la altura máxima:

[tex] y_{max} = v_{0y}t - \frac{1}{2}gt^{2} = 12.3 m/s*1.25 s - \frac{1}{2}9.81 m/s^{2}*(1.25 s)^{2} = 7.7 m [/tex]

b) Podemos encontrar la altura cuando t = 1 s con la misma ecuación (1):

[tex]y_{max} = y_{0} + v_{0y}t - \frac{1}{2}gt^{2} = 12.3 m/s*1 s - \frac{1}{2}9.81 m/s^{2}*(1 s)^{2} = 7.4 m[/tex]

Por lo tanto, la pelota se encontraba a 7.4 m luego de 1 segundo despúes del lanzamiento.

Espero que te sea de utilidad!      

Answer:

d = 120 [m]

Explanation:

In order to solve this problem, we must use the theorem of work and energy conservation. Where the energy in the final state (when the skater stops) is equal to the sum of the mechanical energy in the initial state plus the work done on the skater in the initial state.

The mechanical energy is equal to the sum of the potential energy plus the kinetic energy.  As the track is horizontal there is no unevenness, in this way, there is no potential energy.

E₁ + W₁₋₂ = E₂

where:

E₁  = mechanical energy in the initial state [J] (units of Joules)

W₁₋₂ = work done between the states 1 and 2 [J]

E₂  = mechanical energy in the final state = 0

E₁ = Ek = kinetic energy [J]

E₁ = 0.5*m*v²

where:

m = mass = 60 [kg]

v = initial velocity = 12 [m/s]

Now, the work done is given by the product of the friction force by the distance. In this case, the work is negative because the friction force is acting in opposite direction to the movement of the skater.

W₁₋₂ = -f*d

where:

f = friction force = 36 [N]

d = distance [m]

Now we have:

0.5*m*v² - (f*d) = 0

0.5*60*(12)² - (36*d) = 0

4320 = 36*d

d = 120 [m]

Answer:

8000cm³/hr

Explanation:

Given parameters:

Volume of the liquid draining off per hour   = 8000cm³

Time taken to drain off  = 1hr

Unknown:

Flow rate  = ?

Solution:

Flow rate is the volume of fluid that passes per unit of time.

 Flow rate  = [tex]\frac{volume of fluid}{time taken}[/tex]  

 Flow rate  = [tex]\frac{8000cm^{3} }{1hr}[/tex]  

Flow rate  = 8000cm³/hr

Answer:

a. The student's mistake was that the student did not swing the pendulum and start the watch at the same time.

b. 1.2 s per swing.

c. The likely effect of her reaction time is that they will should subtract two seconds off the time.

Explanation:

The pupil made the error of not simultaneously starting the watch and swinging the pendulum.

Pendulum is defined as a body that is suspended from a fixed point and moves back and forth while being pulled by gravity. The pendulum is used to gauge the gravitational pull because the force of gravity causes it to swing back toward its average position. A pendulum's time period can be used to tell the time because it is constant.

The swing of the pendulum is 1.2 sec. per swing. They should take two seconds off the timing due to her presumably slow reaction time. A pendulum's total time should be divided by the quantity of oscillations in order to determine its time period. When compared to a pendulum with a shorter string, the one back and forth cycle of a longer-stringed pendulum requires more time to complete.

Thus, the pupil made the error of not simultaneously starting the watch and swinging the pendulum.

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Answer:

Momentum is a product of mass and velocity.

Explanation:

Hope this helps you

Crown me as brainliest:)

Answer:

Explanation:

ok it's correct

Answer:

Explanation:

Angle of refraction is the angle made by refracted ray with the normal at the point of incidence . In this figure , refracted ray has been shown by line having arrow-head . Normal has been shown by broken line .

We observe that in figure D , angle made by refracted ray with normal is greatest . So figure D is the answer.

The  image where the angle of refraction is the greatest is the image D

The angle of refraction is the angle that the refracted ray made with the x-axis.

The higher the angle between the refracted ray and the x-axis, the higher the angle of refraction and vice versa.

From the given diagram, we can see that the  image where the angle of refraction is the greatest is the image D

Learn more on angle of refraction here: https://brainly.com/question/15838784

Explanation:

by finding the distance between two successful crest

Answer:

the wavelength can be measured as the distance from crest to crest  or from trough to trough , the wavelength of a wave can be measured as the distance from a point on a wave to the corresponding point on the next cycle of the wave.

Explanation:

Answer:

letterman is shooting the kids

We use insulators to avoid being electrocuted. electricians use rubber gloves to avoid shock. Cables are insolated with rubber so you can hold them without getting shocked even if it is plugged in.

Answer:

92

Explanation:

Answer:

Graphite.

Explanation:

Graphite: "a gray crystalline allotropic form of carbon which occurs as a mineral in some rocks and can be made from coke. It is used as a solid lubricant, in pencils, and as a moderator in nuclear reactors."

Answer:

The required velocity of runner is 4m/s.

Answer:

12m/s2

Explanation:

:D (just a smiley, not answer d)

Answer:

force=1250kg * 30m/s+10

Explanation: it's a change in acceleration

Answer:

1.2 W

Explanation:

Let the value of resistance be R , emf of battery be E

current i = E / R

power = i² R

= E² x R / R²

= E² / R

Given

E² / R = .30

when two batteries are connected

Total emf = 2E

current = 2E / R

Power = ( 2E / R )² x R

= 4 E² / R

= 4 x .30

= 1.2 W .

Answer:

So waves are everywhere. But what makes a wave a wave? What characteristics, properties, or behaviors are shared by the phenomena that we typically characterize as being a wave? How can waves be described in a manner that allows us to understand their basic nature and qualities?

A wave can be described as a disturbance that travels through a medium from one location to another location. Consider a slinky wave as an example of a wave. When the slinky is stretched from end to end and is held at rest, it assumes a natural position known as the equilibrium or rest position. The coils of the slinky naturally assume this position, spaced equally far apart. To introduce a wave into the slinky, the first particle is displaced or moved from its equilibrium or rest position. The particle might be moved upwards or downwards, forwards or backwards; but once moved, it is returned to its original equilibrium or rest position. The act of moving the first coil of the slinky in a given direction and then returning it to its equilibrium position creates a disturbance in the slinky. We can then observe this disturbance moving through the slinky from one end to the other. If the first coil of the slinky is given a single back-and-forth vibration, then we call the observed motion of the disturbance through the slinky a slinky pulse. A pulse is a single disturbance moving through a medium from one location to another location. However, if the first coil of the slinky is continuously and periodically vibrated in a back-and-forth manner, we would observe a repeating disturbance moving within the slinky that endures over some prolonged period of time. The repeating and periodic disturbance that moves through a medium from one location to another is referred to as a wave.

Hope That Helps!!

Explanation:

Answer:

A................

Explanation:

Hope this helps you

A. increase it's current and increase it's voltage

Explanation: