clc
clear all
% exercise 1 - chapter 24
% w=-7r^2+3r+25;
disp('Exercise 1 - Chapter 24')
for r=0:2:40
    w=-7*r^2+3*r+25;
    if w<0
        break
    end
    fprintf('The value of w is %g and r is %g\n',w,r)
end
disp(' ')
% exercise 4 - chapter 24
disp('Exercise 2 - Chapter 24')
R=120;
for t=0:0.1:20
    i=2*t^2-3*t;  % current as a function of time: note the change in formula
    V=i*R;        % voltage formula
    if V>=4
        break
    end
end
fprintf('The voltage is %g V at a time of %g sec\n\n',V,t)