Answer:
-2200 N
Explanation:
Here we can use the impulse theorem, which states that the impulse exerted on Sarah (product of force and duration of collision) is equal to Sarah's change in momentum:
![I=\Delta p\\F \Delta t = m \Delta v](https://tex.z-dn.net/?f=I%3D%5CDelta%20p%5C%5CF%20%5CDelta%20t%20%3D%20m%20%5CDelta%20v)
where
F is the average force
is the duration of the collision
m is the mass
is the change in velocity
In this problem:
m = 55 kg
![\Delta t = 0.5 s](https://tex.z-dn.net/?f=%5CDelta%20t%20%3D%200.5%20s)
Solving the formula, we find the force exerted by the seatbelt on Sarah:
![F=\frac{m\Delta v}{\Delta t}=\frac{(55)(-20)}{0.5}=-2200 N](https://tex.z-dn.net/?f=F%3D%5Cfrac%7Bm%5CDelta%20v%7D%7B%5CDelta%20t%7D%3D%5Cfrac%7B%2855%29%28-20%29%7D%7B0.5%7D%3D-2200%20N)
And the negative sign means the direction is opposite to that of Sarah's initial motion.
The correct answer for this question is D) <span>Threshold frequency depends on the work function of a metal.
</span><span>It does not depend on intensity. Intensity of light only affects the number of electrons ejected. Threshold frequency is dependent on the type of metal . It is not determined by the incident photon . Each metal has its own threshold frequency. So the most feasible answer is d.</span>
Answer:
A large elliptical
Explanation:
A S0 type galaxy is a large elliptical.
Answer:how long it took him to get there
Explanation: