Atrain moving west with an initial velocity of 20 m/s accelerates at 4m/s^2 for 10 seconds. during this time, the train moves a distance of

Explanation:

Now from how I have learned it, we integrate straight from Newton's second law F=ma.

Here we are setting up the problem by writing down F=ma, and then setting it equal to our problem, I used α for the acceleration given in the problem. Next, we integrate from a = α to vf = αt + vi, where vf is the final velocity, vi is the initial velocity, α is our problem's acceleration, and t is our total time. We then proceed to integrate again from that to xf = αt^2/2 + vit + xi where xf is our final position, and xi is our starting position. For the problem we can say that he started from 0m, so the xi = 0m. After plugging in our values we do some algebra to solve for xf, which turns out to be 400m.

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27