ð Unit 2: Energy & Momentum â Mid-Unit Diagnostic
Assessment FOR Learning
ð Not Graded
Purpose: Teacher identifies gaps before unit test. Show all reasoning.
Knowledge & Understanding
Q1 [4 marks]
A roller coaster car (\(600\text{ kg}\) with riders) starts from rest at the top of a \(35\text{ m}\) hill. At the bottom, it enters a loop of radius \(12\text{ m}\).
a) What is the car's speed at the bottom? (Ignore friction.)
b) What is the normal force on the car at the bottom of the loop?
Thinking
Q2 [4 marks]
A \(3.0\text{ kg}\) ball moving east at \(4.0\text{ m/s}\) collides with a \(2.0\text{ kg}\) ball moving west at \(6.0\text{ m/s}\). They stick together.
a) What is the velocity after collision?
b) What fraction of kinetic energy was lost?
Reflection
Q3
Explain in your own words why momentum is always conserved in collisions but kinetic energy is not. What happens to the "lost" energy?