Answer:
The car stops in 7.78s and does not spare the child.
Explanation:
In order to know if the car stops before the distance to the child, you take into account the following equation:
(1)
vo: initial speed of the car = 45km/h
a: deceleration of the car = 2 m/s^2
t: time
xo: initial distance to the child = 25m
x: final distance to the child = 0m
It is necessary that the solution of the equation (1) for time t are real.
You first convert the initial speed to m/s, then replace the values of the parameters and solve the quadratic polynomial for t:
![45\frac{km}{h}*\frac{1h}{3600s}*\frac{1000m}{1km}=12.5\frac{m}{s}](https://tex.z-dn.net/?f=45%5Cfrac%7Bkm%7D%7Bh%7D%2A%5Cfrac%7B1h%7D%7B3600s%7D%2A%5Cfrac%7B1000m%7D%7B1km%7D%3D12.5%5Cfrac%7Bm%7D%7Bs%7D)
![0=25+12.5t-2t^2\\\\2t^2-12.5t-25=0\\\\t_{1,2}=\frac{-(-12.5)\pm \sqrt{(-12.5)^2-4(2)(-25)}}{2(2)}\\\\t_{1,2}=\frac{12.25\pm 18.87}{4}\\\\t_1=7.78s\\\\t_2=-1.65s](https://tex.z-dn.net/?f=0%3D25%2B12.5t-2t%5E2%5C%5C%5C%5C2t%5E2-12.5t-25%3D0%5C%5C%5C%5Ct_%7B1%2C2%7D%3D%5Cfrac%7B-%28-12.5%29%5Cpm%20%5Csqrt%7B%28-12.5%29%5E2-4%282%29%28-25%29%7D%7D%7B2%282%29%7D%5C%5C%5C%5Ct_%7B1%2C2%7D%3D%5Cfrac%7B12.25%5Cpm%2018.87%7D%7B4%7D%5C%5C%5C%5Ct_1%3D7.78s%5C%5C%5C%5Ct_2%3D-1.65s)
You take the first value t1 because it has physical meaning.
The solution for t is real, then, the car stops in 7.78s and does not spare the child.
I think the best answer is: poor driving attitude. If you have a poor attitude, you can make mistakes, such as risky chances or bad choices. The other options might be annoying, but they won't make you make mistakes unless you have a bad attitude.
Answer:
Two objects will have the equal velocities but the forces on both of them will not be equal. The equal velocities of these objects are due to their equal acceleration.
Explanation:
From the newton's equation
![v^{2} -u^{2} = 2as](https://tex.z-dn.net/?f=v%5E%7B2%7D%20-u%5E%7B2%7D%20%3D%202as)
so here we can say that velocity does not depends on the mass.
The acceleration of both objects will be same but not the forces because
F = Ma
As the force is depending on the mass so it will not be the same for both objects.
9,200 Joules is the answer. I got that by multiplying 460N by 20.0m because W=d*f
Answer: Because of the polarity of water molecules
Molecular <u>cohesion</u> is the attraction that molecules have for others of their same type. Depending on the intensity of this attraction, a substance is in a solid, liquid or gaseous state.
In this sense, water (
) can stick to itself through hydrogen bonds, because a water molecule consists of 2 hydrogen atoms attached to 1 oxygen atom.
The oxygen atom tends to monopolize more electrons and keeps them away from hydrogen. Then, it can be said that a water molecule will have a negative side (oxygen) and a positive side (hydrogen).
<u>Thanks to this polarity</u>, water molecules can stick together with the formation of<u> hydrogen bonds</u> to attract a partial positive charge of hydrogen and a more electronegative atom, such as oxygen.