[5]suppose a 1,600 kg car is traveling at 20.0 m/s. what average force is needed to stop the car in 4.0 s?
8.0 × 103 n < < < <
5.0 n
130,000 n
64,000 n
is this correct?

For positive constants a and b, the force between two atoms in a molecule is given f(r) = −a r2 + b r3 , where r > 0 is the distance between the atoms. note: a and b are upper case letters. (a) find f '(r) = (b) find the critical point for f(r). r = (c) find f ''(r) = (d) find the value of r so that f ''(r) = 0.