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trapecia [35]
3 years ago
15

I was driving along at 20 m/s , trying to change a CD and not watching where I was going. When I looked up, I found myself 46 m

from a railroad crossing. And wouldn't you know it, a train moving at 29 m/s was only 56 m from the crossing. In a split second, I realized that the train was going to beat me to the crossing and that I didn't have enough distance to stop. My only hope was to accelerate enough to cross the tracks before the train arrived. If my reaction time before starting to accelerate was 0.42 s , what minimum acceleration did my car need for me to be here today writing these words?
Physics
1 answer:
vampirchik [111]3 years ago
5 0

Answer:

6.46393559312 m/s²

Explanation:

Time taken to cover 56 m

t=\dfrac{56}{29}\ s

Distance covered in 0.42 seconds

0.42\times 20=8.4\ m

From equation of linear motion

s=ut+\frac{1}{2}at^2

8.4+20(\dfrac{56}{29}-0.42)+\dfrac{1}{2}a(\dfrac{56}{29}-0.42)^2=46\\\Rightarrow a=(46-8.4-20(\dfrac{56}{29}-0.42))\times\dfrac{2}{(\dfrac{56}{29}-0.42)^2}\\\Rightarrow a=6.46393559312\ m/s^2

The minimum acceleration is 6.46393559312 m/s²

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An electric field of intensity 3.25 kN/C is applied along the x-axis. Calculate the electric flux through a rectangular plane 0.
jekas [21]

Answer:

\varphi_1= 796.25 N m^2/C

\varphi_2= 0 N m^2/C

\varphi_3=686.1  N m^2/C

Explanation:

From the question we are told that

Electric field of intensity E= 3.25 kN/C

Rectangle parameter Width W=0.350 m  Length L=0.700 m

Angle to the normal \angle=30.5 \textdegree

Generally the equation for Electric flux at parallel to the yz plane \varphi_1 is mathematically given by

\varphi_1=EA cos theta

\varphi_1=3.25* 10^3 N/C * ( 0.350)(0.700) cos 0

\varphi_1= 796.25 N m^2/C

Generally the equation for Electric flux at parallel to xy  plane \varphi_2 is mathematically given by

\varphi_2=EA cos theta

\varphi_2=3.25* 10^3 N/C * ( 0.350)(0.700) cos 90

\varphi_2= 0 N m^2/C

Generally the equation for Electric flux at angle 30 to x plane \varphi_3 is mathematically given by

\varphi_3=EA cos theta

\varphi_3=3.25* 10^3 N/C * ( 0.350)(0.700) cos 30.5

\varphi_3=686.072219  N m^2/C

\varphi_3=686.1  N m^2/C

7 0
3 years ago
Need Help !
Bad White [126]

Answer: 5.96m/s

Explanation:

Given the following :

Mass of car (m) = 1500kg

Velocity (V) = 5.25m/s

Forward force of engine = 1250N

Diatance moved = 4.8m

Final Velocity =?

Final kinetic energy = Initial kinetic energy + work done by engine

Initial kinetic energy = 0.5 × mass × velocity^2

Initial kinetic energy = 0.5 × 1500 × 5.25^2

Initial kinetic energy = 20671.875 J

Work done by engine = Force × distance

Work done by engine = 1250 × 4.8 = 6000J

Final kinetic energy = (20671.875 + 6000) J

= 26671.875 J

From kinetic energy = 0.5mv^2

26671.875 = 1/2 × 1500 × v^2

53343.75 = 1500v^2

v^2 = 35.5625

v = sqrt(35.5625)

v = 5.96m/s

3 0
2 years ago
A
ale4655 [162]

m = 43.2 kg

Explanation:

volume of sphere = (4/3)pi(r)^3

= (4/3)(3.14)(2 m)^3

= 33.5 m^3

density = mass/volume

or solving for mass m,

m = (density)×(volume)

= (1.29 kg/m^3)(33.5 m^3)

= 43.2 kg

3 0
2 years ago
In a single-slit diffraction experiment, a coherent light source illuminates a slit in a barrier, and the resulting pattern is p
UkoKoshka [18]

Answer:

hsjdsdddwqdqwdd

Explanation:

4 0
2 years ago
Which element has an atomic number of 9 and an atomic mass of 19?
yan [13]

Answer:

fluorine

Explanation:

3 0
3 years ago
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