R = a + bs
to find a and b, solve
a+20b = 265
a+30b = 365
then find a+80b
The resistance QR to the motion of a car is partly constant and varies as the square of the speed. At 20km/hr it is 265N. And at 30km/hr it is 365N. Find the resistance at 80km/hr
3 answers
QR = a s^2 + c
265N = a 20^2 + c = 400 a + c
365N = a 30^2 + c = 900 a + c
subtracting equations (to eliminate c) ... 500 a = 100N
solve for a , then substitute back to find c
use the new equation to find QR at 80km/hr
265N = a 20^2 + c = 400 a + c
365N = a 30^2 + c = 900 a + c
subtracting equations (to eliminate c) ... 500 a = 100N
solve for a , then substitute back to find c
use the new equation to find QR at 80km/hr
oops ... my bad. I missed the "square" part.
But I'm sure you caught it before R_Scott did ... right?
But I'm sure you caught it before R_Scott did ... right?
5 answers