About <span>216.6 seconds if my math is correct.</span>
Answer:
Explanation:
In case of rotational motion, every particle is rotated with a same angular velocity .
The relation between linear velocity and angular velocity is
V = r w
Where v is linear velocity, r is the radius of circular path and w be the angular velocity.
Here w is same for all the particles but every particle has different radius of circular path I which they are rotating, so linear velocity is differnet for all.
Answer: A glass object receives a positive charge of +3 nC by rubbing it with a silk cloth. In the rubbing process electrons been removed from it.
Explanation:
It is known that for every atom the protons and neutrons reside in the nucleus of the atom. Whereas electrons move outside the nucleus of an atom. As a result, electrons are able to transfer more easily from one substance to another as compared to the protons.
This is because protons are tightly held by the nucleus of an atom. Whereas electrons are mobile in nature and hence, they can easily move.
Therefore, positive charge on the glass develops due to the removal of electrons from it.
thus, we can conclude that in the given process electrons been removed from the glass object.
Answer:at 21.6 min they were separated by 12 km
Explanation:
We can consider the next diagram
B2------15km/h------->Dock
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B1 at 20km/h
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V
So by the time B1 leaves, being B2 traveling at constant 15km/h and getting to the dock one hour later means it was at 15km from the dock, the other boat, B1 is at a distance at a given time, considering constant speed of 20km/h*t going south, where t is in hours, meanwhile from the dock the B2 is at a distance of (15km-15km/h*t), t=0, when it is 8pm.
Then we have a right triangle and the distance from boat B1 to boat B2, can be measured as the square root of (15-15*t)^2 +(20*t)^2. We are looking for a minimum, then we have to find the derivative with respect to t. This is 5*(25*t-9)/(sqrt(25*t^2-18*t+9)), this derivative is zero at t=9/25=0,36 h = 21.6 min, now to be sure it is a minimum we apply the second derivative criteria that states that if the second derivative at the given critical point is positive it means here we have a minimum, and by calculating the second derivative we find it is 720/(25 t^2 - 18 t + 9)^(3/2) that is positive at t=9/25, then we have our answer. And besides replacing the value of t we get the distance is 12 km.
