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kenny6666 [7]
2 years ago
5

You testify as an "expert witness" in a case involving an accident in which car A slid into the rear of car B, which was stopped

at a red light along a road headed down a hill. You find that the slope of the hill is θ = 12.0°, that the cars were separated by distance d = 25.0 m when the driver of car A put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car A at the onset of braking was v0 = 18.0 m/s.
(a) With what speed did car A hit car B if the coefficient of kinetic friction was 0.60 (dry road surface)?
____ m/s

(b) What was the speed if the coefficient of kinetic friction was 0.10 (road surface covered with wet leaves)?
____ m/s
Physics
1 answer:
natulia [17]2 years ago
3 0

F=mgsinα –F(fr)=

= mgsinα - μmgcosα

a=F/m =g(sinα – μcosα)

=9.8(sin14-0.57•cos14)= -3.04 m/s²

v²=v₀²+2ad

v=sqrt{ v₀²+2ad} =

=sqrt{18²+2• (-3.04) •25}=13.1 m/

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A white dwarf is:______.
bija089 [108]

Answer:

the exposed core of a dead star, supported by electron degeneracy pressure.

Explanation:

A white dwarf is a low luminosity exposed core of a dead star having mass comparable to the sun but volume comparable to the earth . So its density is very high . These stars have lost the capacity to generate energy through the process of fusion . Due to high gravitational energy , it goes on shrinking but ultimately balanced by electron degeneracy pressure. It is not a main sequence star as it has lost the power of fusion .

6 0
3 years ago
A projectile is launched from the ground with an initial velocity of 12ms at an angle of 30° above the horizontal. The projectil
netineya [11]

vi^{2}sin2thita/g =12^{2}sin2[30]/9.8=12.7Answer:

Explanation:

range is given as

6 0
3 years ago
Read 2 more answers
A mass of 1 slug, when attached to a spring, stretches it 2 feet and then comes to rest in the equilibrium position. Starting at
Vesna [10]

Answer:

Y=(\dfrac{3}{16}+t \dfrac{3}{8})e^{-2t}-\dfrac{3}{16}cos 4t

Explanation:

Given that m= 1 slug and given that spring stretches by 2 feet so we can find the spring constant K

mg=k x

1 x 32= k x 2

K=16

And also give that damping force is 8 times the velocity so damping constant C=8.

We know that equation for spring mass system

my''+Cy'+Ky=F

Now by putting the values

1 y"+8 y'+ 16y=6 cos 4 t ----(1)

The general solution of equation Y=CF+IP

Lets assume that at steady state the equation of y will be

y(IP)=A cos 4t+ B sin 4t

To find the constant A and B we have to compare this equation with equation 1.

Now find y' and y" (by differentiate with respect to t)

y'= -4A sin 4t+4B cos 4t

y"=-16A cos 4t-16B sin 4t

Now put the values of y" , y' and y in equation 1

1 (-16A cos 4t-16B sin 4t)+8( -4A sin 4t+4B cos 4t)+16(A cos 4t+ B sin 4t)=6sin4 t

So by comparing the coefficient both sides

-16A+32B+16A=0  So B=0

-16 B-32 A+16B=6  So A=-3/16

y=-3/16 cos 4t

Now to find the CF  of differential equation 1

y"+8 y'+ 16y=6 cos 4 t

Homogeneous version of above equation

m^2+8m+16=0

So CF =(C_1+tC_2)e^{-2t}

So the general equation

Y=(C_1+tC_2)e^{-2t}-3/16 cos 4t

Given that t=0 Y=0 So

C_1=\dfrac{3}{16}

t=0 Y'=0 So

C_2 =\dfrac{3}{8}

Y=(\dfrac{3}{16}+t \dfrac{3}{8})e^{-2t}-\dfrac{3}{16}cos 4t

The above equation is the general equation for motion.

3 0
3 years ago
Trying to explain a solar eclipse is an example of?
zimovet [89]

Answer:

scientific inquiry.

Explanation:

scientific inquiry. Scientific inquiry encompasses the many methods through which scientists investigate the nature of reality and provide interpretations based on the data gathered.

4 0
2 years ago
If you seal a container of air at room temperature (20.0 degrees celcius) and then put it in the refrigerator (2.00 degrees celc
zheka24 [161]

The pressure inside the container will be <u>9.39×10⁴Pa</u>

At constant volume, the pressure in a container is directly proportional to its absolute temperature.

If air in a container is sealed at 20⁰C at a pressure equal to the atmospheric pressure and cooled to 2.00⁰C, the pressure inside the container falls.

Convert the temperature in Celsius to Kelvin.

T_1=20.0^oC+273.15=293.15K\\T_2=2.00^oC+273.15=275.15K

Use the expression for the pressure law.

\frac{P_2}{P_1} =\frac{T_2}{T_1}

Substitute 100,000 Pa for P₁, 293.16 K for T₁ and 275.15K for T₂.

\frac{P_2}{P_1} =\frac{T_2}{T_1}\\ P_2=P_1(\frac{T_2}{T_1})\\ =(100,000Pa)(\frac{275.15K}{293.15K} )\\ =9.386*10^4Pa

The pressure in the container (correct to 2 sf) is <u>9.39×10⁴Pa</u>

6 0
2 years ago
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