The answer is C. The ball and floor had friction between them causing the ball to stop rolling
First, let us assign the variables
y = 0.90 m, x= 15 m,
![h_{0}](https://tex.z-dn.net/?f=%20h_%7B0%7D%20)
= 2.80 m
s= required
The vertical component of the trajectory is in uniformly accelerated motion. The equation is:
![y= v_{0,y} t+ \frac{1}{2} a t^{2} + h_{0}](https://tex.z-dn.net/?f=y%3D%20v_%7B0%2Cy%7D%20t%2B%20%5Cfrac%7B1%7D%7B2%7D%20a%20t%5E%7B2%7D%20%2B%20h_%7B0%7D%20)
, while the horizontal component is
![x= v_{0,x} t](https://tex.z-dn.net/?f=x%3D%20v_%7B0%2Cx%7D%20t)
. Also,
![v_{0,y} =0](https://tex.z-dn.net/?f=%20v_%7B0%2Cy%7D%20%3D0)
since the object starts from rest (with respect to the downward motion). a is negative because it is moving downwards (a = -9.81 m/s^2). Substituting,
![0.9= 0+ \frac{1}{2} (-9.81m/ s^{2} ) ( \frac{x}{ v_{0,x} } )^{2} + h_{0}](https://tex.z-dn.net/?f=0.9%3D%200%2B%20%5Cfrac%7B1%7D%7B2%7D%20%28-9.81m%2F%20s%5E%7B2%7D%20%29%20%28%20%5Cfrac%7Bx%7D%7B%20v_%7B0%2Cx%7D%20%7D%20%29%5E%7B2%7D%20%2B%20h_%7B0%7D%20)
![0.9= 0+ \frac{1}{2} (-9.81m/ s^{2} ) ( \frac{15}{ v_{0,x} } )^{2} + 2.5](https://tex.z-dn.net/?f=0.9%3D%200%2B%20%5Cfrac%7B1%7D%7B2%7D%20%28-9.81m%2F%20s%5E%7B2%7D%20%29%20%28%20%5Cfrac%7B15%7D%7B%20v_%7B0%2Cx%7D%20%7D%20%29%5E%7B2%7D%20%2B%202.5)
The magnitude of v0, which is speed (s), is equal to 24.1 m/s
The initial velocity of a car that accelerates at a constant rate of 3m/s² for 5 seconds is 12m/s.
CALCULATE INITIAL VELOCITY:
The initial velocity of the car can be calculated by using one of the equation of motion as follows:
V = u + at
Where;
- V = final velocity (m/s)
- u = initial velocity (m/s)
- a = acceleration due to gravity (m/s²)
- t = time (s)
According to this question, a car accelerates at a constant rate of 3 m/s² for 5 seconds. If it reaches a velocity of 27 m/s, its initial velocity is calculated as follows:
u = v - at
u = 27 - 3(5)
u = 27 - 15
u = 12m/s.
Therefore, the initial velocity of a car that accelerates at a constant rate of 3m/s² for 5 seconds is 12m/s.
Learn more about motion at: brainly.com/question/974124
Speed must an electron have if its momentum is to be the same as that of an x-ray photon with a wavelength of 0. 85 nm is 8.6*10^5m/s.
To find the answer, we have to know about the energy of photon.
<h3>What is the speed of the electron here?</h3>
- As we know that the momentum of an x-ray photon with a wavelength w,
![P=\frac{h}{w}](https://tex.z-dn.net/?f=P%3D%5Cfrac%7Bh%7D%7Bw%7D)
where; h is the plank's constant.
- Thus, the momentum will be,
![P=\frac{6.63*10^{-34}}{0.85*10^{-9}} =7.8*10^{-25}kgm/s.](https://tex.z-dn.net/?f=P%3D%5Cfrac%7B6.63%2A10%5E%7B-34%7D%7D%7B0.85%2A10%5E%7B-9%7D%7D%20%3D7.8%2A10%5E%7B-25%7Dkgm%2Fs.)
- We have to find the speed of the electron, thus, we have the expression of linear momentum as,
![P=mv\\v=\frac{P}{m} =\frac{7.8*10^{-25}}{9.1*10^{-31}}=8.6*10^5m/s.](https://tex.z-dn.net/?f=P%3Dmv%5C%5Cv%3D%5Cfrac%7BP%7D%7Bm%7D%20%3D%5Cfrac%7B7.8%2A10%5E%7B-25%7D%7D%7B9.1%2A10%5E%7B-31%7D%7D%3D8.6%2A10%5E5m%2Fs.)
Thus, we can conclude that, speed must an electron have if its momentum is to be the same as that of an x-ray photon with a wavelength of 0. 85 nm is 8.6*10^5m/s.
Learn more about the energy of photon here:
brainly.com/question/3584036
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