Answer:
1. Rutherford did the scattering experiment and observed that some of the rays bounce back. He concluded that there is a mass in which positive charge is concentrated. This marks the discovery of nucleus.
2. J.J Thomson discovered electrons by conducting cathode ray experiment.
3. Dalton postulated that matter is made up of small particles caled atoms
The magnitude of the force required to change the length of a spring-like object is directly proportional to the spring constant and the displacement of the spring. Elastic potential energy is directly proportional to the square of the change in length and the spring constant.
