State Hooke's Law.
For forces up to 90 N90\text{ N}90 N, a spring obeys Hooke's Law. A force of 90 N90\text{ N}90 N causes an extension of 60 mm60\text{ mm}60 mm. Calculate the spring constant kkk of the spring in N/m\text{N/m}N/m.
A student makes a spring balance using this spring. The maximum reading of this balance is 110 N110\text{ N}110 N. The student tests his balance with a known weight of 105 N105\text{ N}105 N. He observes that the reading of the balance is not 105 N105\text{ N}105 N. Suggest and explain why the reading is not 105 N105\text{ N}105 N.
183 exam-style questions on CIE IGCSE Physics 1.5.1a Forces, resultant force and motion. Each one has a worked solution and a mark scheme showing where the marks go.