Hookes Law and Spring Constants Warm Up F

Hooke’s Law and Spring Constants

Warm Up F = -kx A spring stretches by 18 cm when a bag of potatoes weighing 56 N is suspended from its end. 1. Determine the spring constant. 2. If the bag of potatoes is replaced with a bag of turnips and the spring is stretch to 15 cm, how much do the turnips weigh (in Newtons)? In kg?

Practice F = -kx A spring stretches by 18 cm when a bag of potatoes weighing 56 N is suspended from its end. 1. Determine the spring constant. 3. 1 N/cm 1. If the bag of potatoes is replaced with a bag of turnips and the spring is stretch to 15 cm, how much do the turnips weigh (in Newtons)? 46. 7 N 4. 78 kg

Hooke’s law • “The magnitude of the force exerted by a spring is equal to the spring constant times the distance the spring is stretched or compressed from its equilibrium position” F=-kx F is force (N) k is the spring constant (N/m) or (N/cm) x is the distance from equilibrium (m) or (cm) Why “-”? Because the force is in the opposite direction that the spring is being stretched! (don’t worry too much…)

Spring Constants • The larger the spring constant, the stiffer the spring • The smaller the spring constant, the stretchier the spring

Potential Energy in a Spring •

A spring is stretched 20 cm and has a spring constant of 5 N/cm. What is the Potential energy stored in the spring? • A spring has a 50 N force hanging from it and is stretched 0. 33 meters. What is the potential energy stored in the spring?