Therein lies the utility of a spring: a simple relationship exists between its length and the forces it’s exerting on its ends. The spring scale can determine how much force it’s exerting on the apple by measuring the length of its spring. The springs consist of a wire coil that pulls inward on its ends when it’s stretched and pushes outward on them when it’s compressed. If a coil on the spring is neither stretched nor compressed, it exerts no forces on its ends, they are in equilibrium – experiencing zero net force, so that the object doesn’t accelerate. When you sit still in a chair, for example, you are in equilibrium. If the spring returns to its natural length, no matter how you distort the spring, then it’s equilibrium. If we pull the free end to the right and don’t let go, the spring exerts a steady inward force on that right end, trying to return it to its original equilibrium position. The more we stretch the spring, the more inward force it exerts on the end. This inward force is exactly proportional to how far we stretch the end away from its original equilibrium position. The force is always directed so as to return the spring to its equilibrium length. This force is called restoring force. The spring’s restoring force is proportional to how far it has been distorted (stretched or compressed) from its equilibrium length. These …show more content…
The larger the spring constant – that is, the firmer the spring – the larger the restoring force the spring exerts for a given distortion. The negative sign indicates that a restoring force always points in the direction opposite the distortion. Some springs are soft and have small spring constant (springs in the toaster), others – firm and have large spring constants (automobile chassis). When you step on a bathroom scale, you depress its surface and levers inside it pull on hidden spring. That spring stretches until it exerts, through the levers, an upward force on you that is equal to your weight. However, the wheel rocks briefly back and forth around your actual weight before it settles down. The wheel moves because you bouncing up and down as the scale gets rid of excess energy. You bouncing up and down because you have excess energy that is shifting back and forth between gravitational potential energy, kinetic energy, and elastic potential energy. This bouncing continues until sliding friction in the scale has converted it all into thermal energy. Only then the bouncing stop and the scale read your correct