When a 4.32 kg object is hung vertically on a certain light spring that obeys hooke's law, the spring stretches 2.92 cm.

(a) if the 4.32 kg object is removed, how far will the spring stretch if a 1.50 kg block is hung on it?

(b) how much work must an external agent do to stretch the same spring 4.00 cm from its unstretched position?

(a) 1.01 cm

First of all, we need to find the spring constant of the spring.

The force initially applied to the spring is equal to the weight of the block hanging on it:

where m = 4.32 kg is the mass of the block and g = 9.8 m/s^2 is the acceleration of gravity.

When this force is applied, the spring stretches by

We can find the spring constant by using Hooke's law:

where k is the spring constant. Solving for k,

Later, the first object is removed and another object of mass

m' = 1.50 kg

is hung on the spring. The weight of this object is

So, if we use Hooke's law again, we can find the new stretching of the spring:

(b) 1.16 J

The work that must be done on the spring is equal to the elastic potential energy that would be stored in the spring, therefore:

where we have

k = 1448.6 N/m is the spring constant

x = 4.00 cm = 0.04 m is the new stretching

Solving the equation, we find the work that must be done by the external force:

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.