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VICPhysicsQuick questions
Unit 2: How does physics help us to understand the world?
Quick questions on Newton's laws and momentum: VCE Physics Unit 2 Year 11
15short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is force-time graph?Show answer
The area under a force-time graph equals the impulse (= change in momentum).
What is first law?Show answer
An object at rest stays at rest, and an object in motion stays in motion at constant velocity, unless acted on by a net external force.
What is second law?Show answer
. The net force on an object equals its mass times its acceleration. Force and acceleration are vectors in the same direction.
What is third law?Show answer
For every action, there is an equal and opposite reaction. If A exerts a force on B, then B exerts an equal-magnitude, opposite-direction force on A.
What is elastic collision?Show answer
Both momentum and kinetic energy are conserved. Examples: collisions between hard balls (close to elastic in practice).
What is inelastic collision?Show answer
Momentum conserved; kinetic energy not (some lost to heat, sound, deformation).
What is perfectly inelastic?Show answer
The two objects stick together after collision. Maximum kinetic energy loss for given initial conditions.
What is car safety?Show answer
Crumple zones extend the time of a collision, reducing the force (impulse-momentum theorem: ). Larger means smaller .
What is rocket propulsion?Show answer
Reaction mass expelled backwards gives forward momentum to the rocket (Newton's third law / conservation of momentum).
What are sports?Show answer
Follow-through in tennis or golf extends contact time to deliver more impulse.
What is momentum is a vector?Show answer
Direction matters. In 1D, sign indicates direction.
What is action-reaction pair on same object?Show answer
The two third-law forces act on different bodies. They do not cancel; they obey Newton's third law together.
What is q1?Show answer
State Newton's second law and define impulse. [2 marks]
What is q2?Show answer
A kg car travelling at m s brakes to rest in s. Calculate (a) the deceleration, (b) the average braking force, and (c) the impulse delivered. [5 marks]
What is q3?Show answer
Refer to the Port of Melbourne crane example. (a) Calculate the tension during acceleration. (b) Determine the impulse delivered.