Skip to main content

Back to the full dot-point answer

WalesPhysicsQuick questions

Unit 1 Motion, Energy and Matter

Quick questions on Dynamics: Newton's laws and conservation of momentum - WJEC A-Level Physics

4short 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 are newton's three laws?
Show answer
For constant mass the second law reduces to F=maF = ma, because ΔpΔt=Δ(mv)Δt=mΔvΔt=ma\dfrac{\Delta p}{\Delta t} = \dfrac{\Delta(mv)}{\Delta t} = m\dfrac{\Delta v}{\Delta t} = ma. The momentum form is the more general statement and is the one WJEC expects when the mass is changing, as in a rocket.
What is conservation of momentum?
Show answer
It follows directly from Newton's third law: the equal and opposite forces during a collision act for the same time, so they produce equal and opposite impulses, and the momentum gained by one body equals the momentum lost by the other.
What is q1?
Show answer
A 0.20 kg0.20\,\text{kg} ball moving at 5.0 m s−15.0\,\text{m s}^{-1} is brought to rest in 0.10 s0.10\,\text{s}. Find the average force on it. [3 marks]
What is q2?
Show answer
State what is conserved in an inelastic collision and what is not. [2 marks]

Have a question we have not covered?

This dot-point answer is short enough that we have not extracted many short questions yet. Read the full dot-point answer or ask Mo, our study assistant, in the chat for follow ups.

All PhysicsQ&A pages