In this question use g=9.8g = 9.8g=9.8 m s−2^{-2}−2
A particle of mass 5 kg rests on a smooth horizontal floor.
A force of magnitude P P\,P newtons is applied to the particle, acting vertically upwards.
Given that P=20P = 20P=20, find the magnitude of the normal reaction of the floor on the particle.
Find the value of P P\,P for which the particle is on the point of leaving the floor.
Given instead that P=69P = 69P=69, find the magnitude and direction of the acceleration of the particle.
139 exam-style questions on AQA A Level Maths 3.3 R: Forces and Newton's laws, covering 3.3.1 Concept of a force and Newton's first law, 3.3.2 Newton's second law, 3.3.3 Weight and motion under gravity, 3.3.4 Newton's third law and equilibrium, 3.3.5 Addition of forces and resultants (A-level only), and 3.3.6 Friction (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.