Free-body diagrams and Newton's lawsEdexcel International A Level Physics: Flashcards

What these 14 flashcards ask

What does a free-body diagram show?
What is the centre of gravity?
State Newton's first law.
State Newton's second law for constant mass.
What is the acceleration of an object when the resultant force is zero?
State the equation for weight.
What is gravitational field strength?
What is the value of g at the Earth's surface?
What is terminal velocity?
Why does the acceleration of a skydiver decrease as they fall?
State Newton's third law.
What two features show that a book's weight and the table's contact force are not a third law pair?
In the free-fall core practical, what graph gives g?
Why do all objects fall with acceleration g when air resistance is negligible?

Exam questions on Free-body diagrams and Newton's laws

A book of mass 1.5 kg rests on a horizontal table. The gravitational field strength is 9.81 N kg⁻¹.
A student says that the weight of the book and the normal contact force of the table on the book are a Newton's third law pair because they are equal and opposite. Give two reasons why the student is wrong.2 marks
A van of mass 1500 kg travels along a straight, level road. The driving force from the engine is 3200 N and the total resistive force is 800 N.
The driver stops accelerating and the driving force becomes zero. The resistive force is still 800 N. Calculate the magnitude of the deceleration of the van.2 marks
A person of mass 70 kg stands on the floor of a lift. The gravitational field strength is 9.81 N kg⁻¹.
The lift accelerates upwards at 1.2 m s⁻². Calculate the force the floor exerts on the person.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).