Answer:
The answer of this question is =1.258*10-4
Most geologists accept radiometric dating techniques as valid because radioactive elements decay at a constant and measurable rate.
Answer: Option C
<u>Explanation:</u>
Scientists prefer radioactive dating to carbon dating because it is more accurate in measuring. The analysis depends upon the radioactive decay of radioactive isotopes of any matter in a given rock or soil.
The parent atoms and daughter atoms are compared while studying, and hence age can be calculated easily. Radioactive decay depends upon the given half-life of the atom, which is a constant and is known. So, it would be very easy to calculate the number of progeny atoms and parent atoms and find out their age.
Answer:
a. ![-12.7 Nm](https://tex.z-dn.net/?f=-12.7%20Nm)
b. ![-7.9 rad/s^2](https://tex.z-dn.net/?f=-7.9%20rad%2Fs%5E2)
Explanation:
I have attached an illustration of a solid disk with the respective forces applied, as stated in this question.
Forces applied to the solid disk include:
![F_1 = 90.0N\\F_2 = 125N](https://tex.z-dn.net/?f=F_1%20%3D%2090.0N%5C%5CF_2%20%3D%20125N)
Other parameters given include:
Mass of solid disk, ![M = 24.3kg](https://tex.z-dn.net/?f=M%20%3D%2024.3kg)
and radius of solid disk, ![r = 0.364m](https://tex.z-dn.net/?f=r%20%3D%200.364m)
a.) The formula for determining torque (
), is ![T = r * F](https://tex.z-dn.net/?f=T%20%3D%20r%20%2A%20F)
Hence the net torque produced by the two forces is given as a summation of both forces:
![T = T_{125} + T_{90}\\= -r(125)sin90 + r(90)sin90\\= 0.364(-125 + 90)\\= -12.7 Nm](https://tex.z-dn.net/?f=T%20%3D%20T_%7B125%7D%20%2B%20T_%7B90%7D%5C%5C%3D%20-r%28125%29sin90%20%2B%20r%2890%29sin90%5C%5C%3D%200.364%28-125%20%2B%2090%29%5C%5C%3D%20-12.7%20Nm)
b.) The angular acceleration of the disk can be found thus:
using the formula for the Moment of Inertia of a solid disk;
![I_{disk} = {\frac{1}{2}}Mr^2](https://tex.z-dn.net/?f=I_%7Bdisk%7D%20%3D%20%7B%5Cfrac%7B1%7D%7B2%7D%7DMr%5E2)
where
= Mass of solid disk
and
= radius of solid disk
We then relate the torque and angular acceleration (
) with the formula:
![T = I\alpha \\-12.7 = ({\frac{1}{2}}Mr^2)\alpha \\\alpha = -{\frac{12.7}{1.61}} = -7.9 rad/s^2](https://tex.z-dn.net/?f=T%20%3D%20I%5Calpha%20%5C%5C-12.7%20%3D%20%28%7B%5Cfrac%7B1%7D%7B2%7D%7DMr%5E2%29%5Calpha%20%5C%5C%5Calpha%20%20%3D%20-%7B%5Cfrac%7B12.7%7D%7B1.61%7D%7D%20%3D%20-7.9%20rad%2Fs%5E2)
1. he traveled a total of 24 miles
2. peter is not moving between 10 and 30 minutes
At the point of maximum displacement (a), the elastic potential energy of the spring is maximum:
![U_i= \frac{1}{2} ka^2](https://tex.z-dn.net/?f=U_i%3D%20%5Cfrac%7B1%7D%7B2%7D%20ka%5E2%20)
while the kinetic energy is zero, because at the maximum displacement the mass is stationary, so its velocity is zero:
![K_i =0](https://tex.z-dn.net/?f=K_i%20%3D0)
And the total energy of the system is
![E_i = U_i+K= \frac{1}{2}ka^2](https://tex.z-dn.net/?f=E_i%20%3D%20U_i%2BK%3D%20%5Cfrac%7B1%7D%7B2%7Dka%5E2%20)
Viceversa, when the mass reaches the equilibrium position, the elastic potential energy is zero because the displacement x is zero:
![U_f = 0](https://tex.z-dn.net/?f=U_f%20%3D%200)
while the mass is moving at speed v, and therefore the kinetic energy is
![K_f = \frac{1}{2} mv^2](https://tex.z-dn.net/?f=K_f%20%3D%20%20%5Cfrac%7B1%7D%7B2%7D%20mv%5E2%20)
And the total energy is
![E_f = U_f + K_f = \frac{1}{2} mv^2](https://tex.z-dn.net/?f=E_f%20%3D%20U_f%20%2B%20K_f%20%3D%20%20%5Cfrac%7B1%7D%7B2%7D%20mv%5E2%20)
For the law of conservation of energy, the total energy must be conserved, therefore
![E_i = E_f](https://tex.z-dn.net/?f=E_i%20%3D%20E_f)
. So we can write
![\frac{1}{2} ka^2 = \frac{1}{2}mv^2](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B2%7D%20ka%5E2%20%3D%20%20%5Cfrac%7B1%7D%7B2%7Dmv%5E2%20%20)
that we can solve to find an expression for v: