State two properties of an object that may be changed by the action of forces.
A fitness trainer uses a training bar that consists of four identical springs connected in parallel between two handles. Each spring has an unstretched length of 0.45 m0.45\text{ m}0.45 m.
Two people stretch the training bar by pulling on the handles in opposite directions.
The springs obey Hooke's law. Explain what is meant by this statement.
Each person pulls the handle on their side with a force of 800 N800\text{ N}800 N.
State the tension in each spring.
Each person pulls the handle on their side with a force of 800 N800\text{ N}800 N.
The training bar stretches and each spring is now 0.70 m0.70\text{ m}0.70 m long. Calculate the spring constant kkk of each spring.
State the energy changes taking place as the muscles are used to stretch the training bar.
245 exam-style questions on CIE IGCSE Physics 1.5 Forces, covering 1.5.1a Forces, resultant force and motion, 1.5.1b Load–extension graphs and the spring constant, 1.5.1c Friction and drag, 1.5.1d Force, mass and acceleration, 1.5.1e Motion in a circular path, 1.5.2a Moment of a force, 1.5.2b Principle of moments and equilibrium, and 1.5.3 Centre of gravity and stability. Each one has a worked solution and a mark scheme showing where the marks go.