A car of mass 1000 kg pulls a trailer of mass 250 kg along a straight horizontal road.
The car and trailer are connected by a light rigid towbar parallel to the road.
The engine of the car produces a constant driving force of D D\,D newtons. The resistance to the motion of the car is 400 N and the resistance to the motion of the trailer is 100 N.
The car and trailer accelerate at 1.2 m s−2^{-2}−2.
Find the value of DDD.
Find the tension in the towbar.
The towbar suddenly breaks. Immediately afterwards, the resistance to the motion of the trailer is unchanged. Find the magnitude and direction of the acceleration of the trailer immediately after the towbar breaks.
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.