Intelligent assessment and revision tools for OCR A Physics

A 0.50 kg lab trolley travels at +2.0 m/s along a low-friction track and collides head-on with an interchangeable end bumper. For both bumpers, the contact time is 0.10 s. With soft bumper S the trolley sticks and comes to rest. With springy bumper B the trolley rebounds at −1.5 m/s. Which statement must be true about the average force on the trolley during the contact in S compared with B?

• A The average force magnitude is 1.75 times larger with B than with S; in both cases it acts opposite the initial motion.
• B The average force magnitudes are equal because the trolley loses similar speeds and the contact times are the same.
• C The average force magnitude is larger with S because more energy is dissipated when it sticks.
• D The average force magnitude with B is smaller, proportional to the 0.5 m/s difference between the initial and rebound speeds.