If a spring has a natural length of 5 cm and a force of 30 n is required to maintain the spring stretched to a length of 9 cm, find the spring constant.

F = k*d, k = F/d.

Force = spring constant * distance.

F = 40, d = (9-5)/100 = 0.04m (extension in metres).

k = 30 / 0.04 = 750.

Answer: it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.explanation:   we have equation of motion ,where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.average velocity = displacement/ time taken.average velocity = 10.69 miles/hr = 10.69*1.6*1000/(60*60) = 4.75 m/s4.75 = s/ts = 4. 1we also have acceleration = 2.18 m/s², initial velocity = 0 m/sso it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.