-0 m/s
- average velocity=displacement/time
- the runners displacement is zero so her average velocity must be zero
B. 100% sure
Have a good day/night
Answer:
t = 1.098*RC
Explanation:
In order to calculate the time that the capacitor takes to reach 2/3 of its maximum charge, you use the following formula for the charge of the capacitor:
![Q=Q_{max}[1-e^{-\frac{t}{RC}}]](https://tex.z-dn.net/?f=Q%3DQ_%7Bmax%7D%5B1-e%5E%7B-%5Cfrac%7Bt%7D%7BRC%7D%7D%5D)
(1)
Qmax: maximum charge capacity of the capacitor
t: time
R: resistor of the circuit
C: capacitance of the circuit
When the capacitor has 2/3 of its maximum charge, you have that
Q=(2/3)Qmax
You replace the previous expression for Q in the equation (1), and use properties of logarithms to solve for t:
![Q=\frac{2}{3}Q_{max}=Q_{max}[1-e^{-\frac{t}{RC}}]\\\\\frac{2}{3}=1-e^{-\frac{t}{RC}}\\\\e^{-\frac{t}{RC}}=\frac{1}{3}\\\\-\frac{t}{RC}=ln(\frac{1}{3})\\\\t=-RCln(\frac{1}{3})=1.098RC](https://tex.z-dn.net/?f=Q%3D%5Cfrac%7B2%7D%7B3%7DQ_%7Bmax%7D%3DQ_%7Bmax%7D%5B1-e%5E%7B-%5Cfrac%7Bt%7D%7BRC%7D%7D%5D%5C%5C%5C%5C%5Cfrac%7B2%7D%7B3%7D%3D1-e%5E%7B-%5Cfrac%7Bt%7D%7BRC%7D%7D%5C%5C%5C%5Ce%5E%7B-%5Cfrac%7Bt%7D%7BRC%7D%7D%3D%5Cfrac%7B1%7D%7B3%7D%5C%5C%5C%5C-%5Cfrac%7Bt%7D%7BRC%7D%3Dln%28%5Cfrac%7B1%7D%7B3%7D%29%5C%5C%5C%5Ct%3D-RCln%28%5Cfrac%7B1%7D%7B3%7D%29%3D1.098RC)
The charge in the capacitor reaches 2/3 of its maximum charge in a time equal to 1.098RC
Answer:
Value that the spring constant k = 12Mg / h
Explanation:
According to 2nd law of Newton:
upward force of the spring= F
The weight of the elevator W = mg
F = Mg = M(5g)
==> F =6Mg.
As the spring is compressed to its maximum distance ie s,the maximum upward acceleration comes just , Hence
F =ks = 6Mg
==> s = 6Mg/k
We have gravitational potential energy turning into elastic potential of the spring as the elevator starts at the top some distance h from the spring, and undergoes a total change in height equal to h + s, so:
Mg(h+s) = 1/2ks2
And plugging in our expression for s:
Mg(h+6Mg/k)= 1/2k(6Mg / k)2
gh + 6M2g2/k = 1/2k(36M2g2 /k2)
Mgh +6M2g2/k = 1/2k(36M2g2 /k2)
gh + 6Mg2/k = 18Mg2 / k
gh = 12Mg2 / k
h = 12Mg / k
k = 12Mg / h
Answer:
a jacket closing mechanism a most useful tool to preserve and protect.
Explanation:
